java歸併排序

標籤：

基本排序：歸併（Merge）排序法是將兩個（或兩個以上）有序表合并成一個新的有序表，即把待排序序列分為若干個子序列，每個子序列是有序的。然後再把有序子序列合并為整體有序序列。

 1 public static void main(String[] args){ 2         int a[] = {34, 8, 64, 51, 32, 21}; 3         mergeSort(a, 0, a.length-1); 4         for (int i = 0; i < a.length; i++) { 5             System.out.print(a[i] + " "); 6         } 7     } 8      9     public static void  mergeSort(int[] a, int left, int right) {10         if (left < right) {11             int center = (left+right)/2;12             mergeSort(a, left, center);13             mergeSort(a, center+1, right);14             merge(a, left, center, right);15         }16     }17     18     public static void merge(int[] a, int left, int center, int right) {19         int[] tmpArr = new int[a.length];20         int mid = center+1;21         int third = left;22         int tmp = left;23         24         while (left <= center && mid <= right) {25             if (a[left] <= a[mid]) {26                 tmpArr[third++] = a[left++];27             } else {28                 tmpArr[third++] = a[mid++];29             }30         }31         while (mid <= right) {32             tmpArr[third++] = a[mid++];33         }34         while (left <= center) {35             tmpArr[third++] = a[left++];36         }37         38         while (tmp <= right) {39             a[tmp] = tmpArr[tmp++];40         }41     }

 

java歸併排序