LeetCode 912. Sort an Array

原题链接在这里：https://leetcode.com/problems/sort-an-array/

题目：

Given an array of integers nums, sort the array in ascending order.

Example 1:

Input: nums = [5,2,3,1]
Output: [1,2,3,5]

Example 2:

Input: nums = [5,1,1,2,0,0]
Output: [0,0,1,1,2,5]

Constraints:

• 1 <= nums.length <= 50000
• -50000 <= nums[i] <= 50000

题解：

Use quick sort and get result.

Time Complexity: O(nlogn).

Space: O(logn). stack space.

AC Java:

class Solution {
    public List<Integer> sortArray(int[] nums) {
        List<Integer> res = new ArrayList<>();
        if(nums == null || nums.length == 0){
            return res;
        }
        
        quickSort(nums, 0, nums.length - 1);
        for(int num : nums){
            res.add(num);
        }
        
        return res;
    }
    
    private void quickSort(int [] nums, int l, int r){
        if(l >= r){
            return;
        }
        
        int m = partition(nums, l, r);
        quickSort(nums, l, m);
        quickSort(nums, m + 1, r);
    }
    
    private int partition(int [] nums, int l, int r){
        int pivot = nums[l];
        while(l < r){
            while(l < r && nums[r] >= pivot){
                r--;
            }
            
            nums[l] = nums[r];
            
            while(l < r && nums[l] <= pivot){
                l++;
            }
            
            nums[r] = nums[l];
        }
        
        nums[l] = pivot;
        return l;
    }
}