数据结构之--归并排序的实现

import java.util.Arrays;

public class MergeSort {  
 
    public static int[] sort(int[] nums, int low, int high) {  
        int mid = (low + high) / 2;  
        if (low < high) {  
            // 左边  
            sort(nums, low, mid);  
            // 右边  
            sort(nums, mid + 1, high);  
            // 左右归并  
            merge(nums, low, mid, high);  
        }  
        return nums;  
    }  
  
    public static void merge(int[] nums, int low, int mid, int high) {  
        int[] temp = new int[high - low + 1];  
        int i = low;// 左指针  
        int j = mid + 1;// 右指针  
        int k = 0;  
  
        // 把较小的数先移到新数组中  
        while (i <= mid && j <= high) {  
            if (nums[i] < nums[j]) {  
                temp[k++] = nums[i++];  
            } else {  
                temp[k++] = nums[j++];  
            }  
        }  
  
        // 把左边剩余的数移入数组  
        while (i <= mid) {  
            temp[k++] = nums[i++];  
        }  
  
        // 把右边边剩余的数移入数组  
        while (j <= high) {  
            temp[k++] = nums[j++];  
        }  
  
        // 把新数组中的数覆盖nums数组  
        for (int k2 = 0; k2 < temp.length; k2++) {  
            nums[k2 + low] = temp[k2];  
        }  
    }  
  
      
    // 归并排序的实现  
    public static void main(String[] args) {  
  
        int[] array1 = { 2, 7, 8, 3, 1, 6, 9, 0, 5, 4 };  
  
        MergeSort.sort(array1, 0, array1.length-1);  
        System.out.println(Arrays.toString(array1));  
        
        int[] array2 = {9, 1, 5, 3, 4, 2, 6, 8, 7};
        MergeSort.sort(array2, 0, array2.length-1);
        System.out.println(Arrays.toString(array2)); 
    }  
}