题目描述

leecode第912题：排序数组：

给你一个整数数组 nums，请你将该数组升序排列。

示例 1：

输入：nums = [5,2,3,1]
输出：[1,2,3,5]

示例 2：

输入：nums = [5,1,1,2,0,0]
输出：[0,0,1,1,2,5]

提示：

1 <= nums.length <= 5 * 104
-5 * 104 <= nums[i] <= 5 * 104

代码：

//归并排序优化
class Solution {
public:vector<int> sortArray(vector<int>& nums) {int len = nums.size();//优化1：全局使用一份临时数组int *temp = new int[len];mergeSort(nums, 0, len - 1, temp);return nums;}void mergeSort(vector<int>& nums, int left, int right, int* temp){if(right == left){return;}int mid = left + (right - left)/2;mergeSort(nums, left, mid, temp);mergeSort(nums, mid + 1, right, temp);//优化2：在两部分数组已经有序的情况下，不再合并if(nums[mid] < nums[mid+1]){return;}mergeOfTwoSortedArray(nums, left, mid, right, temp);}void mergeOfTwoSortedArray(vector<int>& nums, int left, int mid, int right, int* temp){for(int i = left; i<=right; i++){temp[i] = nums[i];}int i = left, j = mid + 1;for(int k = left; k<=right; k++){if(i == mid+1){nums[k] = temp[j];j++;}else if(j == right + 1){nums[k] = temp[i];i++;}else if(temp[i] <= temp[j]){//这一行的else没写曾经耗费了很长时间排查nums[k] = temp[i];i++;}else if(temp[i] > temp[j]){nums[k] = temp[j];j++;}}}
};