排序算法 归并排序

归并排序

private static void mergeSort(int[] nums, int left, int right, int[] temp) {
    if (left == right) {
        return;
    }
    int mid = left + (right - left) / 2;
    mergeSort(nums, left, mid, temp);
    mergeSort(nums, mid + 1, right, temp);
    merge(nums, left, mid, right, temp);
}

private static void merge(int[] nums, int left, int mid, int right, int[] temp) {
    int i = left, j = mid + 1;
    for (int k = left; k <= right; k++) {
        if (i == mid + 1) {
            temp[k] = nums[j++];
        } else if (j == right + 1) {
            temp[k] = nums[i++];
        } else if (nums[i] <= nums[j]) {
            temp[k] = nums[i++];
        } else {
            temp[k] = nums[j++];
        }
    }
    for (int k = left; k <= right; k++) {
        nums[k] = temp[k];
    }
}


 public static void main(String[] args) {
     int[] num = {7,5,6,4,8,9,6,7,4,5,9,0,7,3};
     System.out.println("未排序");
     System.out.println(Arrays.toString(num));
     int[] temp = new int[num.length];
     mergeSort(num, 0, num.length - 1, temp);
     System.out.println("排序后");
     System.out.println(Arrays.toString(num));
 }