題目要求

Find the length of the longest substring T of a given string (consists of lowercase letters only) such that every character in T appears no less than k times.Example 1:Input: s = "aaabb", k = 3Output: 3The longest substring is "aaa", as 'a' is repeated 3 times. Example 2:Input: s = "ababbc", k = 2Output: 5The longest substring is "ababb", as 'a' is repeated 2 times and 'b' is repeated 3 times.

找出字符串中的最長(zhǎng)子字符串，滿足該子字符串中任何字符出現(xiàn)的次數(shù)都大于k。

思路和代碼

這是一個(gè)經(jīng)典的分治法解決的問(wèn)題，關(guān)鍵在于我們?nèi)绾螌⑦@個(gè)問(wèn)題分解為更小的子問(wèn)題。反過(guò)來(lái)想，這個(gè)子字符串一定不包含什么元素呢？當(dāng)一個(gè)元素出現(xiàn)的總次數(shù)小于k，那么該元素一定不在子字符串中，只需要將其作為分界點(diǎn)，分別找出左半部分和右半部分的滿足條件的最長(zhǎng)子字符串。

public int longestSubstring(String s, int k) {return longestSubstring(s, k, 0, s.length()-1);}public int longestSubstring(String s, int k, int left, int right) {if(left > right) {return 0;}int[] count = new int[26];for(int i = left ; i<=right ; i++) {count[s.charAt(i) - 'a']++;}int result = right - left + 1;for(int i = left ; i<=right ; i++) {if(count[s.charAt(i)-'a'] < k && count[s.charAt(i)-'a'] > 0) {int leftLongest = longestSubstring(s, k, left, i-1);int rightLongest = longestSubstring(s, k, i+1, right);result = Math.max(leftLongest, rightLongest);break;}}return result;} 創(chuàng)作挑戰(zhàn)賽新人創(chuàng)作獎(jiǎng)勵(lì)來(lái)咯，堅(jiān)持創(chuàng)作打卡瓜分現(xiàn)金大獎(jiǎng)

總結(jié)

以上是生活随笔為你收集整理的395. Longest Substring with At Least K Repeating Characters的全部?jī)?nèi)容，希望文章能夠幫你解決所遇到的問(wèn)題。

如果覺(jué)得生活随笔網(wǎng)站內(nèi)容還不錯(cuò)，歡迎將生活随笔推薦給好友。