java七大排序——7_归并排序

归并排序：

将数组分为2块，再到每一小块再分为两块，直到最后一个元素为一块，然后进行有序数组合并，最终合并为一个有序数组
代码实现

public static void mergeSorts ( int[] array){ mergeSortsInternal(array,0,array.length)//mergeSortsInternalNoR(array);}/*** 归并排序：递归内部排序*/public static void mergeSortInternal ( int[] array, int low, int high){if (low + 1 >= high) {//[low,high)return;}int mid = (low + high) / 2;mergeSortInternal(array, low, mid);mergeSortInternal(array, mid, high);merge(array, low, mid, high);}private static void merge ( int[] array, int low, int mid, int high){int length = high - low;int[] extral = new int[length];//[low,mid]//[mid,high]int less = low;int great = mid;int i = 0;while (less < mid && great < high) {if (array[less] <= array[great]) {extral[i] = array[less];less++;i++;} else {extral[i] = array[great];great++;i++;}}while (less < mid) {extral[i++] = array[less++];}while (great < high) {extral[i++] = array[great++];}for (int j = 0; j < length; j++) {array[low + j] = extral[j];}}