版權(quán)聲明：本文為博主原創(chuàng)文章，未經(jīng)博主允許不得轉(zhuǎn)載。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/85112591
作者： 負(fù)雪明燭
id：?? ?fuxuemingzhu
個(gè)人博客：?? ?http://fuxuemingzhu.cn/

把自己刷過(guò)的所有題目做一個(gè)整理，并且用簡(jiǎn)潔的語(yǔ)言概括了一下思路，匯總成了一個(gè)表格。

題目的排列順序是按照先Easy再M(fèi)edium再Hard排列的，暫時(shí)還沒(méi)有把題目全部整理完成。后序我會(huì)把刷過(guò)的所有的題目都整理到這個(gè)文檔里。

題目?? ?難度?? ?解法?? ?題目地址
566. Reshape the Matrix?? ?Easy?? ?變長(zhǎng)數(shù)組，求余法，維護(hù)行列計(jì)算在新的數(shù)組中的位置?? ?https://blog.csdn.net/fuxuemingzhu/article/details/83626519
897. Increasing Order Search Tree?? ?Easy?? ?直接中序遍歷的結(jié)果放到鏈表結(jié)尾?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82349263
771. Jewels and Stones?? ?Easy?? ?字典統(tǒng)計(jì)次數(shù)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79188903
929. Unique Email Addresses?? ?Easy?? ?字符串+set統(tǒng)計(jì)個(gè)數(shù)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/83478570
709. To Lower Case?? ?Easy?? ?ASIIC碼操作ord,chr?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81015228
804. Unique Morse Code Words?? ?Easy?? ?字典映射 + set統(tǒng)計(jì)個(gè)數(shù)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79774003
905. Sort Array By Parity?? ?Easy?? ?自定義sorted函數(shù)的cmp為數(shù)字mod 2?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82732066
461. Hamming Distance?? ?Easy?? ?先異或 再數(shù)1的個(gè)數(shù)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54138423
657. Robot Return to Origin?? ?Easy?? ?Counter統(tǒng)計(jì)，判斷是否相等?? ?https://blog.csdn.net/fuxuemingzhu/article/details/83663650
832. Flipping an Image?? ?Easy?? ?直接計(jì)算新的數(shù)組的每個(gè)位置的值即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/80471495
617. Merge Two Binary Trees?? ?Easy?? ?樹(shù)的遞歸操作?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79052953
28. Implement strStr()?? ?Easy?? ?字符串遍歷+切片是否相等的判斷?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79254558
890. Find and Replace Pattern?? ?Easy?? ?直接使用字典做映射?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82014687
814. Binary Tree Pruning?? ?Medium?? ?二叉樹(shù)的后序遍歷?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79858752
561. Array Partition I?? ?Easy?? ?排序+求和?? ?https://blog.csdn.net/fuxuemingzhu/article/details/71412574
728. Self Dividing Numbers?? ?Easy?? ?直接遍歷區(qū)間的每個(gè)數(shù)字進(jìn)行判斷?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79053113
852. Peak Index in a Mountain Array?? ?Easy?? ?二分查找的變種，使用Mid位置和左右位置比較?? ?https://blog.csdn.net/fuxuemingzhu/article/details/80721162
922. Sort Array By Parity II?? ?Easy?? ?分別求出奇偶數(shù)組然后拼接?? ?https://blog.csdn.net/fuxuemingzhu/article/details/83045735
883. Projection Area of 3D Shapes?? ?Easy?? ?分別計(jì)算三視圖的面積即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81748335
908. Smallest Range I?? ?Easy?? ?直接數(shù)學(xué)計(jì)算?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82824685
867. Transpose Matrix?? ?Easy?? ?先構(gòu)建數(shù)組再遍歷實(shí)現(xiàn)翻轉(zhuǎn)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81015450
589. N-ary Tree Preorder Traversal?? ?Easy?? ?多叉樹(shù)的先序遍歷，可以用遞歸和迭代?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81021950
590. N-ary Tree Postorder Traversal?? ?Easy?? ?多叉樹(shù)的后序遍歷?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81017965
350. Intersection of Two Arrays II?? ?Easy?? ?先排序然后用兩個(gè)指針移動(dòng)找出數(shù)組交集?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54341965
876. Middle of the Linked List?? ?Easy?? ?快慢指針同時(shí)向鏈表后面移動(dòng)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81748484
700. Search in a Binary Search Tree?? ?Easy?? ?BST中節(jié)點(diǎn)的查找，遞歸?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81015754
933. Number of Recent Calls?? ?Easy?? ?找出滿足一定條件的區(qū)間長(zhǎng)度，可以使用二分或者隊(duì)列?? ?https://blog.csdn.net/fuxuemingzhu/article/details/83714891
559. Maximum Depth of N-ary Tree?? ?Easy?? ?求樹(shù)的高度，可以使用BFS和DFS?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81021864
557. Reverse Words in a String III?? ?Easy?? ?字符串的單詞分別翻轉(zhuǎn)再拼接到一起就好了?? ?https://blog.csdn.net/fuxuemingzhu/article/details/70141268
806. Number of Lines To Write String?? ?Easy?? ?使用字典保存每個(gè)字符的長(zhǎng)度，然后統(tǒng)計(jì)每行的長(zhǎng)度是否超過(guò)100就好了?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79810381
344. Reverse String?? ?Easy?? ?字符串翻轉(zhuǎn)，[::-1?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51284382
811. Subdomain Visit Count?? ?Easy?? ?字典保存每個(gè)子域名出現(xiàn)的次數(shù)即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79789925
476. Number Complement?? ?Easy?? ?求數(shù)字的補(bǔ)數(shù)，方法是異或上與其二進(jìn)制數(shù)字的長(zhǎng)度相等的全1二進(jìn)制數(shù)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54562124
821. Shortest Distance to a Character?? ?Easy?? ?過(guò)兩遍數(shù)組，分別找出距離左邊和右邊的這個(gè)字符的最短距離?? ?https://blog.csdn.net/fuxuemingzhu/article/details/80471765
500. Keyboard Row?? ?Easy?? ?使用字典保存每行元素，然后看每個(gè)單詞是不是只由一行元素組成?? ?https://blog.csdn.net/fuxuemingzhu/article/details/68953517
893. Groups of Special-Equivalent Strings?? ?Easy?? ?把奇偶位置都取出來(lái)，重新拼接成字符串作為指紋，看總的有多少種指紋?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82083609
872. Leaf-Similar Trees?? ?Easy?? ?先序、中序、后序都能得到葉子序列?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81748617
884. Uncommon Words from Two Sentences?? ?Easy?? ?使用字典統(tǒng)計(jì)每個(gè)單詞出現(xiàn)的次數(shù)，然后看字典keys()的交集，然后在字典中看是不是只出現(xiàn)了一次?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81749170
766. Toeplitz Matrix?? ?Easy?? ?判斷每個(gè)斜線是否相等，方法是判斷每個(gè)元素是否和其左上角元素相等?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79127213
463. Island Perimeter?? ?Easy?? ?求小島的周長(zhǎng)。使用所有陸地個(gè)數(shù)×4-相交部分×2.?? ?https://blog.csdn.net/fuxuemingzhu/article/details/83868905
682. Baseball Game?? ?Easy?? ?用一個(gè)棧進(jìn)行模擬?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79183412
868. Binary Gap?? ?Easy?? ?二進(jìn)制表示中1的最大間距，保留上一個(gè)1的位置即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81079495
104. Maximum Depth of Binary Tree?? ?Easy?? ?二叉樹(shù)的高度，可以用DFS和BFS?? ?https://blog.csdn.net/fuxuemingzhu/article/details/48490829
136. Single Number?? ?Easy?? ?所有的數(shù)字出現(xiàn)了兩次，其中一個(gè)只出現(xiàn)了一次。找出這個(gè)數(shù)字的方法可以使用字典統(tǒng)計(jì)或者異或運(yùn)算?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54173334
496. Next Greater Element I?? ?Easy?? ?找出某個(gè)數(shù)字右邊比他大的數(shù)字，直接遍歷查找就好了?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79080337
637. Average of Levels in Binary Tree?? ?Easy?? ?求每層的二叉樹(shù)的均值，可以使用BFS和DFS?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79088554
693. Binary Number with Alternating Bits?? ?Easy?? ?判斷數(shù)字的二進(jìn)制表示是不是01交錯(cuò)的。直接遍歷判斷，或者位運(yùn)算。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79089937
762. Prime Number of Set Bits in Binary Representation?? ?Easy?? ?判斷二進(jìn)制數(shù)字的1的個(gè)數(shù)是不是質(zhì)數(shù)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79089092
917. Reverse Only Letters?? ?Easy?? ?只翻轉(zhuǎn)字母其余字符不動(dòng)，可以使用棧、雙指針?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82956271
292. Nim Game?? ?Easy?? ?判斷輸入數(shù)字是不是4的倍數(shù)即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51284421
824. Goat Latin?? ?Easy?? ?字符串處理，簡(jiǎn)單?? ?https://blog.csdn.net/fuxuemingzhu/article/details/80471925
892. Surface Area of 3D Shapes?? ?Easy?? ?統(tǒng)計(jì)立方體個(gè)數(shù)，減去相交面積?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82083893
784. Letter Case Permutation?? ?Easy?? ?經(jīng)典回溯法，把字符的大小寫(xiě)分別拼接到字符串尾部?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79360330
258. Add Digits?? ?Easy?? ?兩重循環(huán)，一直對(duì)每位數(shù)字求和直到剩余個(gè)位數(shù)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/49161129
283. Move Zeroes?? ?Easy?? ?使用一個(gè)指針指向第一個(gè)為0的位置，然后遍歷不是0的位置進(jìn)行交換?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51284981
748. Shortest Completing Word?? ?Easy?? ?找出符合某個(gè)模式的字符串，直接處理就好了?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79432228
690. Employee Importance?? ?Easy?? ?dfs?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79091343
389. Find the Difference?? ?Easy?? ?找多出來(lái)的字符，可以使用字典，也可以使用異或?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54174443
520. Detect Capital?? ?Easy?? ?統(tǒng)計(jì)大寫(xiě)字符的個(gè)數(shù)，判斷是不是在首位?? ?https://blog.csdn.net/fuxuemingzhu/article/details/68957658
448. Find All Numbers Disappeared in an Array?? ?Easy?? ?用set去重，找出沒(méi)有出現(xiàn)的數(shù)字即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/53981307
696. Count Binary Substrings?? ?Easy?? ?先找出連續(xù)的0，1個(gè)數(shù)，然后進(jìn)行交錯(cuò)求最小值，在求和?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79183556
454. 4Sum II?? ?Easy?? ?4sum，先確定兩個(gè)數(shù)字，然后看剩余兩個(gè)數(shù)字的和是否出現(xiàn)過(guò)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79473739
788. Rotated Digits?? ?Easy?? ?字典保存翻轉(zhuǎn)后的數(shù)字，判斷是否相等即可。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79378135
653. Two Sum IV - Input is a BST?? ?Easy?? ?BFS或者DFS，在遍歷的過(guò)程中進(jìn)行破案噸?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79120732
371. Sum of Two Integers?? ?Easy?? ?位運(yùn)算?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79379939
349. Intersection of Two Arrays?? ?Easy?? ?用兩個(gè)set求交集，然后轉(zhuǎn)成List即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54236183
606. Construct String from Binary Tree?? ?Easy?? ?先序遍歷，可以省略右子樹(shù)，所以需要做一個(gè)節(jié)點(diǎn)是否存在的判斷?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79121550
206. Reverse Linked List?? ?Easy?? ?翻轉(zhuǎn)單鏈表，可以使用遞歸和迭代?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51290121
169. Majority Element?? ?Easy?? ?Moore投票法，或者字典統(tǒng)計(jì)次數(shù)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51288749
171. Excel Sheet Column Number?? ?Easy?? ?26進(jìn)制，沒(méi)有難度?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51286467
13. Roman to Integer?? ?Easy?? ?使用字典保存映射，遍歷求值就好了。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/48208995
937. Reorder Log Files?? ?Easy?? ?分割排序，再拼接?? ?https://blog.csdn.net/fuxuemingzhu/article/details/83961188
121. Best Time to Buy and Sell Stock?? ?Easy?? ?一次遍歷，如果后一天比前一天大就買了賣?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51291151
242. Valid Anagram?? ?Easy?? ?判斷字符串是否是同構(gòu)的，直接統(tǒng)計(jì)詞頻或者排序?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51286195
860. Lemonade Change?? ?Easy?? ?貪心算法，找零錢先找大的面額，如果不夠再用小的面額?? ?https://blog.csdn.net/fuxuemingzhu/article/details/80913955
217. Contains Duplicate?? ?Easy?? ?判斷數(shù)組是否有重復(fù)，可以統(tǒng)計(jì)詞頻，判斷set長(zhǎng)度是否相等，排序等方法?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51289768
427. Construct Quad Tree?? ?Easy?? ?建立四叉樹(shù)，使用遞歸，判斷4個(gè)葉子全部是0或者1?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81836838
706. Design HashMap?? ?Easy?? ?設(shè)計(jì)一個(gè)字典，直接開(kāi)個(gè)很大的數(shù)組即可，內(nèi)存放得下?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81017297
538. Convert BST to Greater Tree?? ?Easy?? ?把每個(gè)節(jié)點(diǎn)變成比它大的節(jié)點(diǎn)的值的和，采用逆中序遍歷。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79132336
100. Same Tree?? ?Easy?? ?判斷兩棵數(shù)是否相等，直接遞歸?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51285076
530. Minimum Absolute Difference in BST?? ?Easy?? ?中序遍歷，保存前一個(gè)節(jié)點(diǎn)，當(dāng)前節(jié)點(diǎn)的值減去前一個(gè)節(jié)點(diǎn)的值?? ?https://blog.csdn.net/fuxuemingzhu/article/details/69666671
783. Minimum Distance Between BST Nodes?? ?Easy?? ?和上題完全一樣?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79402127
383. Ransom Note?? ?Easy?? ?使用字典統(tǒng)計(jì)每個(gè)字符出現(xiàn)的次數(shù)，前者小于后者即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54178342
796. Rotate String?? ?Easy?? ?字符串切片?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79521194
717. 1-bit and 2-bit Characters?? ?Easy?? ?單次遍歷，判斷前面滿足的條件下，最后一位是0即可。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79130681
453. Minimum Moves to Equal Array Elements?? ?Easy?? ?把n-1個(gè)數(shù)字加1，相等于把最大值-1.求和-n*最小值?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54177981
733. Flood Fill?? ?Easy?? ?對(duì)相同顏色進(jìn)行染色，可以使用DFS和BFS.?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79401716
404. Sum of Left Leaves?? ?Easy?? ?求所有左葉子的和，要判斷是不是在左邊，判斷是不是葉子，然后加到結(jié)果中?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54178595
447. Number of Boomerangs?? ?Easy?? ?統(tǒng)計(jì)回旋鏢的個(gè)數(shù)，不能暴力解決，需要使用排列組合公式n*(n-1)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54379349
598. Range Addition II?? ?Easy?? ?求隊(duì)列的最小值即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79398272
492. Construct the Rectangle?? ?Easy?? ?從算術(shù)平方根開(kāi)始找約數(shù)即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/68957959
167. Two Sum II - Input array is sorted?? ?Easy?? ?前后指針同時(shí)向中間走，找到target之后停止?? ?https://blog.csdn.net/fuxuemingzhu/article/details/70232518
387. First Unique Character in a String?? ?Easy?? ?首先做個(gè)字符出現(xiàn)次數(shù)的統(tǒng)計(jì)，然后再次遍歷，找出只出現(xiàn)了一次的第一個(gè)字符。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/84139374
697. Degree of an Array?? ?Easy?? ?求最大的出現(xiàn)次數(shù)的所有數(shù)字，其最左右出現(xiàn)的位置差的最小值?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79146067
455. Assign Cookies?? ?Easy?? ?貪心算法，盡可能給小孩滿足其欲望的餅干?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54177627
108. Convert Sorted Array to Binary Search Tree?? ?Easy?? ?構(gòu)建BST，使用中間數(shù)進(jìn)行分割，用遞歸?? ?https://blog.csdn.net/fuxuemingzhu/article/details/70665213
506. Relative Ranks?? ?Easy?? ?相對(duì)排名，可以使用堆或者排序或者argsort?? ?https://blog.csdn.net/fuxuemingzhu/article/details/70173434
661. Image Smoother?? ?Easy?? ?直接暴力求平均即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79156499
409. Longest Palindrome?? ?Easy?? ?統(tǒng)計(jì)出現(xiàn)次數(shù)的奇偶就可以?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54236594
599. Minimum Index Sum of Two Lists?? ?Easy?? ?保存出現(xiàn)的索引和與元素的對(duì)應(yīng)，使用堆保存最小的就行?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79138621
268. Missing Number?? ?Easy?? ?理論和-當(dāng)前和?? ?https://blog.csdn.net/fuxuemingzhu/article/details/70332471
563. Binary Tree Tilt?? ?Easy?? ?后序遍歷函數(shù)返回的是左右子樹(shù)的差，在里面用變量求和?? ?https://blog.csdn.net/fuxuemingzhu/article/details/71440281
830. Positions of Large Groups?? ?Easy?? ?找到長(zhǎng)度大于3的連續(xù)字符，需要判斷結(jié)束！！?? ?https://blog.csdn.net/fuxuemingzhu/article/details/80472242
350. Intersection of Two Arrays II?? ?Easy?? ?可以排序，也可以使用字典統(tǒng)計(jì)次數(shù)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54341965
543. Diameter of Binary Tree?? ?Easy?? ?遞歸求樹(shù)的深度，同時(shí)求左右兩個(gè)深度的和的最大值?? ?https://blog.csdn.net/fuxuemingzhu/article/details/70338312
551. Student Attendance Record I?? ?Easy?? ?統(tǒng)計(jì)A的個(gè)數(shù)，并且判斷連續(xù)L的個(gè)數(shù)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/70337973
121. Best Time to Buy and Sell Stock?? ?Easy?? ?保存當(dāng)前的最小值以及最大收益即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51291151
628. Maximum Product of Three Numbers?? ?Easy?? ?找出三個(gè)數(shù)最大的乘積?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79169635
401. Binary Watch?? ?Easy?? ?使用combinations函數(shù)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54344098
746. Min Cost Climbing Stairs?? ?Easy?? ?動(dòng)態(tài)規(guī)劃?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79188612
925. Long Pressed Name?? ?Easy?? ?使用雙指針，統(tǒng)計(jì)連續(xù)字符出現(xiàn)的次數(shù)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/83245395
541. Reverse String II?? ?Easy?? ?Python的切片翻轉(zhuǎn)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/70141909
705. Design HashSet?? ?Easy?? ?直接開(kāi)數(shù)組就行?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81016992
107. Binary Tree Level Order Traversal II?? ?Easy?? ?DFS和BFS都可以?? ?https://blog.csdn.net/fuxuemingzhu/article/details/49108449
504. Base 7?? ?Easy?? ?轉(zhuǎn)成7進(jìn)制?? ?https://blog.csdn.net/fuxuemingzhu/article/details/70194688
115. Distinct Subsequences?? ?Easy?? ?動(dòng)規(guī)，判斷當(dāng)前字符是否相等?? ?https://blog.csdn.net/fuxuemingzhu/article/details/84228383
21. Merge Two Sorted Lists?? ?Easy?? ?可以使用遞歸或者迭代?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51291406
458. Poor Pigs?? ?Easy?? ?類似撥號(hào)鍵盤(pán)，多維空間求解?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81079261
257. Binary Tree Paths?? ?Easy?? ?打印二叉樹(shù)的路徑，使用遞歸和迭代?? ?https://blog.csdn.net/fuxuemingzhu/article/details/71249429
844. Backspace String Compare?? ?Easy?? ?字符串可以退格，使用棧輕松解決?? ?https://blog.csdn.net/fuxuemingzhu/article/details/80643408
202. Happy Number?? ?Easy?? ?遞歸和迭代兩種做法?? ?https://blog.csdn.net/fuxuemingzhu/article/details/49180507
674. Longest Continuous Increasing Subsequence?? ?Easy?? ?簡(jiǎn)單的動(dòng)態(tài)規(guī)劃?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79220527
744. Find Smallest Letter Greater Than Target?? ?Easy?? ?線性掃描或者二分?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79137225
118. Pascal’s Triangle?? ?Easy?? ?提前構(gòu)造出來(lái)，然后處理每行即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51346488
671. Second Minimum Node In a Binary Tree?? ?Easy?? ?遞歸的時(shí)候找第二小值?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79222455
720. Longest Word in Dictionary?? ?Easy?? ?先排序，再找前綴是否存在。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79123277
27. Remove Element?? ?Easy?? ?使用雙指針或者標(biāo)記指針使得前面都是滿足要求的，后面都不滿足?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51303161
70. Climbing Stairs?? ?Easy?? ?動(dòng)態(tài)規(guī)劃?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51290778
415. Add Strings?? ?Easy?? ?直接模擬大整數(shù)加法，需要注意進(jìn)位問(wèn)題?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54380737
235. Lowest Common Ancestor of a Binary Search Tree?? ?Easy?? ?BST找公共祖先，使用遞歸很簡(jiǎn)單?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51290289
594. Longest Harmonious Subsequence?? ?Easy?? ?統(tǒng)計(jì)相鄰的數(shù)字是否都存在即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79233752
101. Symmetric Tree?? ?Easy?? ?可以使用BFS和DFS兩種方法?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51345707
53. Maximum Subarray?? ?Easy?? ?動(dòng)態(tài)規(guī)劃找子數(shù)組最大和?? ?https://blog.csdn.net/fuxuemingzhu/article/details/71101802
819. Most Common Word?? ?Easy?? ?正則+統(tǒng)計(jì)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/80472079
231. Power of Two?? ?Easy?? ?判斷二進(jìn)制是不是只有1個(gè)1即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51290981
405. Convert a Number to Hexadecimal?? ?Easy?? ?轉(zhuǎn)成16進(jìn)制，難點(diǎn)在于負(fù)數(shù)的處理：加上1<<32?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54426643
83. Remove Duplicates from Sorted List?? ?Easy?? ?遞歸和循環(huán)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51290506
326. Power of Three?? ?Easy?? ?循環(huán)和迭代?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51290895
191. Number of 1 Bits?? ?Easy?? ?使用位移統(tǒng)計(jì)二進(jìn)制個(gè)數(shù)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51290376
437. Path Sum III?? ?Easy?? ?找路徑的個(gè)數(shù)，使用DFS*2或者BFS+DFS?? ?https://blog.csdn.net/fuxuemingzhu/article/details/71097135
704. Binary Search?? ?Easy?? ?二分的模板?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81017415
119. Pascal’s Triangle II?? ?Easy?? ?原地翻轉(zhuǎn)可以用倒序遍歷?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51348629
232. Implement Queue using Stacks?? ?Easy?? ?兩個(gè)棧實(shí)現(xiàn)一個(gè)隊(duì)列?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51345762
572. Subtree of Another Tree?? ?Easy?? ?DFS*2或DFS+BSF?? ?https://blog.csdn.net/fuxuemingzhu/article/details/71440802
198. House Robber?? ?Easy?? ?簡(jiǎn)單dp，當(dāng)前房間偷和不偷兩種狀態(tài)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51291936
703. Kth Largest Element in a Stream?? ?Easy?? ?使用小根堆維護(hù)k個(gè)值，則第一個(gè)元素就是第k大元素?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81027116
345. Reverse Vowels of a String?? ?Easy?? ?使用棧進(jìn)行翻轉(zhuǎn)，或者使用雙指針?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51291677
66. Plus One?? ?Easy?? ?使用carry表示進(jìn)位?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51346096
263. Ugly Number?? ?Easy?? ?除去2,3,5因子即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/49183961
35. Search Insert Position?? ?Easy?? ?二分查找?? ?https://blog.csdn.net/fuxuemingzhu/article/details/70738108
645. Set Mismatch?? ?Easy?? ?使用統(tǒng)計(jì)次數(shù)或者直接求和計(jì)算?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79247916
747. Largest Number At Least Twice of Others?? ?Easy?? ?找出最大值，然后彈掉，再找次大值即可。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79188909
342. Power of Four?? ?Easy?? ?遞歸和迭代?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51291091
724. Find Pivot Index?? ?Easy?? ?先求和，在遍歷求前半部分的和，找出左邊等于右邊?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79248308
9. Palindrome Number?? ?Easy?? ?可以先翻轉(zhuǎn)成整數(shù)，然后判斷和原來(lái)的是否相等?? ?https://blog.csdn.net/fuxuemingzhu/article/details/71334663
482. License Key Formatting?? ?Easy?? ?計(jì)算第一個(gè)分割的長(zhǎng)度，后面都是等長(zhǎng)的了?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79234075
1. Two Sum?? ?Easy?? ?保存已經(jīng)出現(xiàn)過(guò)的數(shù)字的索引，當(dāng)下次遍歷的時(shí)候遇到了滿足要求的結(jié)果，那么既是停止?? ?https://blog.csdn.net/fuxuemingzhu/article/details/72465759
459. Repeated Substring Pattern?? ?Easy?? ?判斷每個(gè)子串重復(fù)多次能不能組成原來(lái)的串即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/54564801
849. Maximize Distance to Closest Person?? ?Easy?? ?從前向后以及從后向前遍歷兩次，取最近距離?? ?https://blog.csdn.net/fuxuemingzhu/article/details/80643250
38. Count and Say?? ?Easy?? ?統(tǒng)計(jì)字符連續(xù)出現(xiàn)的次數(shù)，并說(shuō)出來(lái)，需要注意最后的一個(gè)字符也要添加上去?? ?https://blog.csdn.net/fuxuemingzhu/article/details/71618640
80. Remove Duplicates from Sorted Array II?? ?Easy?? ?快指針移動(dòng)判斷和慢指針是否相等，如果不等就換到前面來(lái)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82829709
643. Maximum Average Subarray I?? ?Easy?? ?一定注意是長(zhǎng)度為k的滑動(dòng)窗口，注意下標(biāo)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79248629
501. Find Mode in Binary Search Tree?? ?Easy?? ?如果使用附加空間，可以使用字典保存次數(shù)；否則需要遍歷兩次，判斷出現(xiàn)次數(shù)。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/71124600
374. Guess Number Higher or Lower?? ?Easy?? ?使用二分查找?? ?https://blog.csdn.net/fuxuemingzhu/article/details/71516105
743. Network Delay Time?? ?Easy?? ?dijkstra算法?? ?https://leetcode.com/problems/network-delay-time/description/
558. Quad Tree Intersection?? ?Easy?? ?遞歸構(gòu)造?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82356008
172. Factorial Trailing Zeroes?? ?Easy?? ?數(shù)有多少個(gè)5就行了?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51347044
441. Arranging Coins?? ?Easy?? ?二分查找滿足條件的層數(shù)即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/71330733
225. Implement Stack using Queues?? ?Easy?? ?使用一個(gè)隊(duì)列就能實(shí)現(xiàn)棧，每次Push的時(shí)候，把隊(duì)列里的所有元素彈出再放進(jìn)來(lái)就好了。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/72598111
67. Add Binary?? ?Easy?? ?使用進(jìn)位進(jìn)行模擬?? ?ddhttps://blog.csdn.net/fuxuemingzhu/article/details/77341154v
434. Number of Segments in a String?? ?Easy?? ?string.split()默認(rèn)就是按照多個(gè)空格分割?? ?https://blog.csdn.net/fuxuemingzhu/article/details/71194298
112. Path Sum?? ?Easy?? ?遞歸和迭代都能滿足?? ?https://blog.csdn.net/fuxuemingzhu/article/details/71715810
205. Isomorphic Strings?? ?Easy?? ?分別看s到t的映射和t到s的映射是不是一一映射的?? ?https://blog.csdn.net/fuxuemingzhu/article/details/72127108
443. String Compression?? ?Easy?? ?使用Pos變量維護(hù)應(yīng)該放到哪個(gè)位置，然后一次遍歷統(tǒng)計(jì)次數(shù)就好了?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79183289
303. Range Sum Query - Immutable?? ?Easy?? ?保存每個(gè)位置的累積和?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79253036
438. Find All Anagrams in a String?? ?Easy?? ?滑動(dòng)窗口，保存等長(zhǎng)的子字符串中包含的字符數(shù)是否和另外一個(gè)相等?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79184109
20. Valid Parentheses?? ?Easy?? ?使用棧判斷括號(hào)是否合法?? ?https://blog.csdn.net/fuxuemingzhu/article/details/72366868
840. Magic Squares In Grid?? ?Easy?? ?暴力判斷每個(gè)9*9的格子是不是滿足題意的河圖?? ?https://blog.csdn.net/fuxuemingzhu/article/details/80473253
141. Linked List Cycle?? ?Easy?? ?走兩步走一步，看是否重合?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51297249
203. Remove Linked List Elements?? ?Easy?? ?遞歸解法不好想，但是代碼很簡(jiǎn)單?? ?https://blog.csdn.net/fuxuemingzhu/article/details/77340945
234. Palindrome Linked List?? ?Easy?? ?利用一個(gè)數(shù)組保存所有的數(shù)字，然后判斷數(shù)組是不是回文的。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/72597942
111. Minimum Depth of Binary Tree?? ?Easy?? ?DFS/BFS，其實(shí)DFS更難?? ?https://blog.csdn.net/fuxuemingzhu/article/details/48519035
290. Word Pattern?? ?Easy?? ?一一映射?? ?https://blog.csdn.net/fuxuemingzhu/article/details/72528424
155. Min Stack?? ?Easy?? ?使用輔助棧保存最小值?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79253237
219. Contains Duplicate II?? ?Easy?? ?使用字典保存出現(xiàn)的位置，當(dāng)新的元素到來(lái)的時(shí)候，更新字典?? ?https://blog.csdn.net/fuxuemingzhu/article/details/77387169
941. Valid Mountain Array?? ?Easy?? ?兩個(gè)while就可以了?? ?https://blog.csdn.net/fuxuemingzhu/article/details/84206380
88. Merge Sorted Array?? ?Easy?? ?從后向前進(jìn)行遍歷，每次找到大的往后移動(dòng)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/77444695
914. X of a Kind in a Deck of Cards?? ?Easy?? ?需要進(jìn)行一個(gè)遍歷，找到是否存在這個(gè)分組大小?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82914279
680. Valid Palindrome II?? ?Easy?? ?需要用到雙指針，先找到第一個(gè)不相等的位置，然后去除左邊或者右邊，判斷是否是回文?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79252779
687. Longest Univalue Path?? ?Easy?? ?定義的DFS是對(duì)過(guò)root的單臂進(jìn)行循環(huán)，但是更新的結(jié)果是雙臂，有點(diǎn)意思?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79248926
14. Longest Common Prefix?? ?Easy?? ?遍歷最短的子串的每一位，看所有字符串在這一位上是不是相等的?? ?https://blog.csdn.net/fuxuemingzhu/article/details/77561186
686. Repeated String Match?? ?Easy?? ?重復(fù)NB/NA + 3次，看b是不是在a里?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79574835
122.Best Time to Buy and Sell Stock II?? ?Easy?? ?只要每天的比前面一天高，那么就買上并且賣掉即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/70258549
28. Implement strStr()?? ?Easy?? ?循環(huán)加切片?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79254558
475. Heaters?? ?Easy?? ?找出最臨近的距離?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79254295
754. Reach a Number?? ?Easy?? ?數(shù)學(xué)題，非常不喜歡?? ?https://blog.csdn.net/fuxuemingzhu/article/details/84556932
400. Nth Digit?? ?Easy?? ?數(shù)學(xué)計(jì)算第多少位?? ?https://blog.csdn.net/fuxuemingzhu/article/details/84559975
69. Sqrt(x)?? ?Easy?? ?二分查找或者牛頓法?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79254648
581. Shortest Unsorted Continuous Subarray?? ?Easy?? ?先排序，然后比較不等的位置?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79254454
190. Reverse Bits?? ?Easy?? ?翻轉(zhuǎn)二進(jìn)制再轉(zhuǎn)成整數(shù)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79254344
125. Valid Palindrome?? ?Easy?? ?過(guò)濾掉不是字母的字符，然后判斷是不是回文即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79252936
874. Walking Robot Simulation?? ?Easy?? ?模擬整個(gè)過(guò)程即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82356556
532. K-diff Pairs in an Array?? ?Easy?? ?找絕對(duì)值出現(xiàn)等于k的次數(shù)，需要對(duì)k進(jìn)行判斷?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79255633
168. Excel Sheet Column Title?? ?Easy?? ?需要對(duì)26取余，并且做個(gè)判斷，因?yàn)?\26對(duì)26取余的結(jié)果是一樣的?? ?https://blog.csdn.net/fuxuemingzhu/article/details/51286857
189. Rotate Array?? ?Easy?? ?可以使用額外數(shù)組，也可使用遞歸原地翻轉(zhuǎn)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79258753
665. Non-decreasing Array?? ?Easy?? ?找到變小的位置，然后和再前面的數(shù)字進(jìn)行判斷，看是應(yīng)該修改當(dāng)前的還是前面的?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79264475
707. Design Linked List?? ?Easy?? ?自己實(shí)現(xiàn)鏈表，挺復(fù)雜的。可以使用list進(jìn)行模擬，方便很多。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81026066
938. Range Sum of BST?? ?Medium?? ?需要根據(jù)根節(jié)點(diǎn)的值進(jìn)行判斷，郵編和左邊需不需要繼續(xù)尋找?? ?https://blog.csdn.net/fuxuemingzhu/article/details/83961263
807. Max Increase to Keep City Skyline?? ?Medium?? ?分別找出行和咧的最大值，把每個(gè)位置增長(zhǎng)到行列最大值的最小值?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79820383
535. Encode and Decode TinyURL?? ?Medium?? ?使用字典完成映射?? ?https://blog.csdn.net/fuxuemingzhu
654. Maximum Binary Tree?? ?Medium?? ?找到最大值，然后數(shù)組切片?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79265180
701. Insert into a Binary Search Tree?? ?Medium?? ?遞歸解法，直接對(duì)當(dāng)前節(jié)點(diǎn)進(jìn)行操作！?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82385503
890. Find and Replace Pattern?? ?Medium?? ?判斷是不是一一映射?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82014687
921. Minimum Add to Make Parentheses Valid?? ?Medium?? ?使用一個(gè)棧?? ?https://blog.csdn.net/fuxuemingzhu/article/details/83045871
797. All Paths From Source to Target?? ?Medium?? ?回溯法找路徑?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79624149
861. Score After Flipping Matrix?? ?Medium?? ?把行進(jìn)行翻轉(zhuǎn)，按列統(tǒng)計(jì)1的個(gè)數(shù)即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/81118328
894. All Possible Full Binary Trees?? ?Medium?? ?使用兩種循環(huán)遍歷可能構(gòu)成的左子樹(shù)和右子樹(shù)，每次構(gòu)建新的root?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82084204
763. Partition Labels?? ?Medium?? ?使用字典保存每個(gè)字符最后出現(xiàn)的位置，如果一個(gè)區(qū)間內(nèi)字符的最后位置的都在一起，那么就添加到結(jié)果里?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79265829
419. Battleships in a Board?? ?Medium?? ?直接數(shù)有多少小島就行，判斷小島可以使用它的最左上角元素即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79403172
537. Complex Number Multiplication?? ?Medium?? ?復(fù)數(shù)運(yùn)算，重點(diǎn)是分割字符串?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79266080
338. Counting Bits?? ?Medium?? ?i的二進(jìn)制1個(gè)數(shù)等于i/2的二進(jìn)制個(gè)數(shù)+i%2?? ?https://blog.csdn.net/fuxuemingzhu/article/details/70806676
885. Spiral Matrix III?? ?Medium?? ?保留循環(huán)更新步數(shù)，很惡心?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82389223
791. Custom Sort String?? ?Medium?? ?統(tǒng)計(jì)次數(shù)，拼接成字符串?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79378688
442. Find All Duplicates in an Array?? ?Medium?? ?原地變成負(fù)數(shù)，如果已經(jīng)是負(fù)數(shù)，那么說(shuō)明出現(xiàn)了兩次。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79275549
355. Design Twitter?? ?Medium?? ?使用優(yōu)先級(jí)隊(duì)列彈出最新的內(nèi)容?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82155420
841. Keys and Rooms?? ?Medium?? ?可以使用DFS和BFS解決?? ?https://blog.csdn.net/fuxuemingzhu/article/details/80476862
406. Queue Reconstruction by Height?? ?Medium?? ?先插入長(zhǎng)得高的他們不會(huì)影響別人，然后在對(duì)應(yīng)位置插入次高的?? ?https://blog.csdn.net/fuxuemingzhu/article/details/68486884
513. Find Bottom Left Tree Value?? ?Medium?? ?層次遍歷，找出最后一層的第一個(gè)節(jié)點(diǎn)即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/70161829
739. Daily Temperatures?? ?Medium?? ?使用一個(gè)棧，保存每個(gè)元素，如果后面的元素比較大，那么就已知出棧操作?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79285081
946. Validate Stack Sequences?? ?Medium?? ?使用棧進(jìn)行模擬，無(wú)論如何都把當(dāng)前的元素彈出，然后和彈出的元素進(jìn)行比較，相等的話一直彈出?? ?https://blog.csdn.net/fuxuemingzhu/article/details/84495797
515. Find Largest Value in Each Tree Row?? ?Medium?? ?遍歷每一層，找出最大值即可。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/70183314
540. Single Element in a Sorted Array?? ?Medium?? ?可以使用很風(fēng)騷的二分查找k,?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79275636
889. Construct Binary Tree from Preorder and Postorder Traversal?? ?Medium?? ?找到后序的倒數(shù)第二個(gè)元素就是右子樹(shù)的根節(jié)點(diǎn)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82391321
260. Single Number III?? ?Medium?? ?使用異或或者字典解決?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79434100
553. Optimal Division?? ?Medium?? ?這個(gè)題非常tricky，沒(méi)意思?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79403723
647. Palindromic Substrings?? ?Medium?? ?判斷回文，需要判斷去掉兩頭字符之后是否仍然是回文，動(dòng)態(tài)規(guī)劃?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79433960
695. Max Area of Island?? ?Medium?? ?找到島的數(shù)量，這個(gè)題可以使用BFS或者DFS的方法?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79182435
856. Score of Parentheses?? ?Medium?? ?可以使用棧和遞歸，這個(gè)題很巧妙，是個(gè)不錯(cuò)的題目?? ?https://blog.csdn.net/fuxuemingzhu/article/details/84956643
919. Complete Binary Tree Inserter?? ?Medium?? ?使用數(shù)組保存每個(gè)節(jié)點(diǎn)的指針，因?yàn)槭峭耆鏄?shù)，所以節(jié)點(diǎn)位置除以2就得到了它的父親節(jié)點(diǎn)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82958284
451. Sort Characters By Frequency?? ?Medium?? ?根據(jù)出現(xiàn)次數(shù)排序，然后構(gòu)建新的字符串即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79437548
789. Escape The Ghosts?? ?Medium?? ?找出是否存在更小的曼哈頓距離?? ?https://blog.csdn.net/fuxuemingzhu/article/details/80480462
94. Binary Tree Inorder Traversal?? ?Medium?? ?中序遍歷本身很簡(jiǎn)單，但是這個(gè)遞歸的寫(xiě)法不好想?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79294461
865. Smallest Subtree with all the Deepest Nodes?? ?Medium?? ?定義遞歸函數(shù)：返回<最大深度,最大深度對(duì)應(yīng)的節(jié)點(diǎn)>?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82432130
508. Most Frequent Subtree Sum?? ?Medium?? ?遍歷求和，字典統(tǒng)計(jì)出現(xiàn)次數(shù)最多的所有元素?? ?http://www.cnblogs.com/grandyang/p/6481682.html
526. Beautiful Arrangement?? ?Medium?? ?經(jīng)典回溯法，要背會(huì)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79431941
238. Product of Array Except Self?? ?Medium?? ?使用兩次遍歷，分別從左邊和右邊向中間靠攏?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79325534
712. Minimum ASCII Delete Sum for Two Strings?? ?Medium?? ?和LCS很接近的DP題目?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79822689
817. Linked List Components?? ?Medium?? ?判斷當(dāng)前節(jié)點(diǎn)在set中，但是下一個(gè)節(jié)點(diǎn)不在即可?? ?https://blog.csdn.net/fuxuemingzhu/article/details/80479431
347. Top K Frequent Elements?? ?Medium?? ?使用字典統(tǒng)計(jì)次數(shù)，使用優(yōu)先級(jí)隊(duì)列實(shí)現(xiàn)排序?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79294073
462. Minimum Moves to Equal Array Elements II?? ?Medium?? ?找出中位數(shù)，然后求所有數(shù)字到中位數(shù)的距離和?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79437926
46. Permutations?? ?Medium?? ?經(jīng)典回溯法?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79363903
495. Teemo Attacking?? ?Medium?? ?計(jì)算每次中毒的開(kāi)始和結(jié)束時(shí)間?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79438658
22. Generate Parentheses?? ?Medium?? ?經(jīng)典回溯法?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79362373
529. Minesweeper?? ?Medium?? ?掃雷游戲，使用DFS?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79462285
667. Beautiful Arrangement II?? ?Medium?? ?每次把后面最大數(shù)字放到前面來(lái)就能增加一種新的差值?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79437401
677. Map Sum Pairs?? ?Medium?? ?前綴樹(shù)的題目，可以背一背?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79436619
547. Friend Circles?? ?Medium?? ?并查集的題目?? ?https://blog.csdn.net/fuxuemingzhu/article/details/70258103
565. Array Nesting?? ?Medium?? ?一直遍歷就好了，使用一個(gè)visited數(shù)組，但不是回溯。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79460546
947. Most Stones Removed with Same Row or Column?? ?Medium?? ?需要使用并查集，非常考驗(yàn)抽象能力?? ?https://blog.csdn.net/fuxuemingzhu/article/details/84500642
858. Mirror Reflection?? ?Medium?? ?鏡像反射，需要找規(guī)律，分偶數(shù)和奇數(shù)進(jìn)行討論?? ?https://blog.csdn.net/fuxuemingzhu/article/details/82432579
676. Implement Magic Dictionary?? ?Medium?? ?找到存不存在漢明間距是1?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79447934
781. Rabbits in Forest?? ?Medium?? ?對(duì)兔子出現(xiàn)次數(shù)進(jìn)行統(tǒng)計(jì)，然后求一個(gè)公式。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79457764
769. Max Chunks To Make Sorted?? ?Medium?? ?從左到右遍歷一次，時(shí)刻保持當(dāng)前的最大值，如果當(dāng)前最大值等于索引，那么chunck+1.?? ?https://blog.csdn.net/fuxuemingzhu/article/details/80482014
655. Print Binary Tree?? ?Medium?? ?先把二叉樹(shù)構(gòu)造出來(lái)，然后使用類似二分查找左右分治的方法。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79439026
208. Implement Trie (Prefix Tree)?? ?Medium?? ?構(gòu)造字典樹(shù)，是個(gè)好題，需要背會(huì)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79388432
648. Replace Words?? ?Medium?? ?使用字典樹(shù)或者拉鏈法求解?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79391682
421. Maximum XOR of Two Numbers in an Array?? ?Medium?? ?暴力求解會(huì)超時(shí)，需要使用異或的性質(zhì)從最高位開(kāi)始遍歷。或者使用字典樹(shù)。?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79473171
40. Combination Sum II?? ?Medium?? ?經(jīng)典的回溯法，這個(gè)題需要背會(huì)?? ?https://blog.csdn.net/fuxuemingzhu/article/details/79343638
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作者：負(fù)雪明燭?
來(lái)源：CSDN?
原文：https://blog.csdn.net/fuxuemingzhu/article/details/85112591?
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