最近學習了下java，感覺java在基本語法上與C++非常相似。作為練習，我用java實現了冒泡排序、選擇排序、插入排序、基爾排序、快速排序、堆排序、計數排序、合并排序。

以下為實現代碼：

public class Sort{public void print_arr(int[] arr){int len = arr.length;for (int i = 0; i < len; i++){System.out.print("" + arr[i] + " ");}System.out.println("");}public int[] dup_arr(int[] arr){int len = arr.length;int re[] = new int[len];for (int i = 0; i < len; i++){re[i] = arr[i];}return re;}public int[] bubble(int[] arr){int dup[] = this.dup_arr(arr);int len = dup.length;int tmp = 0;for (int i = 0; i < len; i++){for (int j = 0; j < len - 1 - i; j++){if (dup[j] < dup[j+1]){tmp = dup[j];dup[j] = dup[j+1];dup[j+1] = tmp;}}}return dup;}public int[] selection(int[] arr){int dup[] = this.dup_arr(arr);int len = dup.length;int tmp = 0;int max = 0;for (int i = 0; i < len; i++){max = i;for (int j = i + 1; j < len; j++){if (dup[j] > dup[max]){max = j;}}tmp = dup[i];dup[i] = dup[max];dup[max] = tmp;}return dup;}public int[] insertion(int[] arr){int dup[] = this.dup_arr(arr);for (int i = 1; i < dup.length; i++){int key = dup[i];int j = i - 1;while (j >= 0 && dup[j] < key){dup[j + 1] = dup[j];j--;}dup[j + 1] = key;}return dup;}public int[] shell(int[] arr, int step){int dup[] = this.dup_arr(arr);while (step > 0){//insertion sortingfor (int i = step; i < dup.length; i += step){int j = i - step;int key = dup[i];while (j >= 0 && dup[j] < key){dup[j + step] = dup[j];j -= step;}dup[j + step] = key;}step = step / 2;}return dup;}public void quick(int[] dup, int leftpoint, int rightpoint){if (leftpoint >= rightpoint){return;}int key = dup[rightpoint];int left = leftpoint;int right = rightpoint;while (true){while (left < right && dup[left] >= key){left++;}while (left < right && dup[right] <= key){right--;}int tmp = 0;if (left >= right){tmp = dup[right];dup[right] = key;dup[rightpoint] = tmp;break;}tmp = dup[right];dup[right] = dup[left];dup[left] = tmp;}this.quick(dup, leftpoint, left - 1);this.quick(dup, left + 1, rightpoint);}//min heappublic int micro_adjust(int[] arr, int i, int last){if (2 * i + 1 > last){return i;}int max = arr[i] < arr[2 * i + 1] ? i : (2 * i + 1);if (2 * i + 2 > last){return max;}max = arr[max] < arr[2 * i + 2] ? max : (2 * i + 2);if (max != i){int tmp = arr[i];arr[i] = arr[max];arr[max] = tmp;}return max;}//part of heap sorting. build a min heappublic void build_heap(int[] arr, int last){int mid = (last + 1) / 2 - 1;for (int i = mid; i >= 0; i--){int tmp = micro_adjust(arr, i, last);//System.out.print("i: " + i + " tmp: " + tmp + "arr: ");//this.print_arr(arr);int flag = i;while (tmp <= mid && tmp != flag){flag = tmp;tmp = micro_adjust(arr, tmp, last);}}return;}//part of heap sorting. adjust the left arrpublic void adjust_heap(int[] arr, int last){int tmp = arr[0];arr[0] = arr[last];arr[last] = tmp;this.build_heap(arr, last - 1);return;}//use min heap to sort arr from big to smallpublic int[] heap(int[] arr){int dup[] = this.dup_arr(arr);this.build_heap(dup, dup.length - 1);for (int i = 0; i < dup.length; i++){//System.out.print("i: " + i + " arr: ");//this.print_arr(dup);adjust_heap(dup, dup.length - 1 - i);}return dup;} public int[] counting(int[] arr){int min = arr[0];int max = arr[0];for (int i = 1; i < arr.length; i++){min = min < arr[i] ? min : arr[i];max = max > arr[i] ? max : arr[i];}int buckets[] = new int[max - min + 1];int index = 0;for (int i = 0; i < arr.length; i++){index = arr[i] - min;buckets[index]++;}int res[] = new int[arr.length];for (int i = 0; i < res.length; i++){res[i] = -1;}for (int i = 0; i < arr.length; i++){index = arr[i] - min;int cnt = 0;for (int j = 0; j < index; j++){cnt += buckets[j];}while (res[res.length - 1 - cnt] != -1){cnt++;}res[res.length - 1 - cnt] = arr[i];}return res;}/*Failure: don't know how to build the buckets arr ......public int[] radix(int[] arr){int dup[] = this.dup_arr(arr);Queue[] buckets = new Queue[10];for (int i = 0; i < 10; i++){buckets[i] = new LinkedList();}int max = dup[0];for (int i = 1; i < dup.length; i++){max = max > dup[i] ? max : dup[i];}int n = 10;while (max > 0){for (int i = 0; i < dup.length; i++){buckets[dup[i] % n].add(dup[i]);}int j = 0;for (int i = 0; i < 10; i++){ while (!buckets[i].isEmpty()){dup[j++] = buckets[i].getFirst();buckets[i].removeFirst();}}max /= 10;n *= 10;}return dup;}*///part of merge sorting: merge two arr togetherpublic int[] merge(int[] arr1, int[] arr2){int res[] = new int[arr1.length + arr2.length];int i = 0;int j = 0;int k = 0;while (i < arr1.length && j < arr2.length){if (arr1[i] > arr2[j]){res[k++] = arr1[i++];}else{res[k++] = arr2[j++];}}while (i < arr1.length){res[k++] = arr1[i++];}while (j < arr2.length){res[k++] = arr2[j++];}return res;}//the main part of merge_sortpublic int[] merge_sort(int[] arr, int start, int end){//System.out.println("start: " + start + " end: " + end);if (end - start < 1){//System.out.println("end == start");int tmp[] = {arr[start]};return tmp;}int flag = (end - start) / 2;int res1[] = merge_sort(arr, start, start + flag);//System.out.println("res1:");//this.print_arr(res1);int res2[] = merge_sort(arr, start + flag + 1, end);//System.out.println("res2:");//this.print_arr(res2);int res[] = merge(res1, res2);//this.print_arr(res);return res;}public static void main(String[] args){int arr[] = {6, 6, 7, 5, 3, 2, 4, 1, 8, 9, 0};Sort s = new Sort();System.out.print("The original array: ");s.print_arr(arr);System.out.print("after bubble sorting: ");s.print_arr(s.bubble(arr));System.out.print("after selection sorting: ");s.print_arr(s.selection(arr));System.out.print("after insertion sorting: ");s.print_arr(s.insertion(arr));System.out.print("after shell sorting: ");s.print_arr(s.shell(arr, arr.length/2));System.out.print("after quick sorting: ");int dup[] = s.dup_arr(arr);s.quick(dup, 0, dup.length - 1);s.print_arr(dup);System.out.print("after heap sorting: ");s.print_arr(s.heap(arr));System.out.print("after counting sorting: ");s.print_arr(s.counting(arr));//failure: because don't know how to define buckets//System.out.print("after radix sorting: ");//s.print_arr(s.radix(arr));//failure: because don't know how to define buckets//System.out.print("after buckets sorting: ");//s.print_arr(s.buckets(arr)); System.out.print("after merge sorting: ");dup = s.dup_arr(arr);s.print_arr(s.merge_sort(dup, 0, dup.length - 1));} } View Code

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轉載于:https://www.cnblogs.com/sunada2005/p/3341131.html

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