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class Solution {

    int partition(vector<int>& nums, int left, int right) {

        int i = left + rand() % (right - left + 1);
        int pivot = nums[i];

        swap(nums[i], nums[left]);

        i = left + 1;
        int j = right;
        while (true) {
            while (i <= j && nums[i] < pivot) {
                i++;
            }

            while (i <= j && nums[j] > pivot) {
                j--;
            }

            if (i >= j) {
                break;
            }

            swap(nums[i], nums[j]);
            i++;
            j--;
        }
        swap(nums[left], nums[j]);
        return j;
    }

    // 快速排序子数组 [left, right]
    void quick_sort(vector<int>& nums, int left, int right) {
   
        bool ordered = true;
        for (int i = left; i < right; i++) {
            if (nums[i] > nums[i + 1]) {
                ordered = false;
                break;
            }
        }
        if (ordered) {
            return;
        }

        int i = partition(nums, left, right); 
        quick_sort(nums, left, i - 1);  
        quick_sort(nums, i + 1, right); 
   }

public:
    vector<int> sortArray(vector<int>& nums) {
        quick_sort(nums, 0, (int) nums.size() - 1);
        return nums;
    }
};

https://leetcode.cn/problems/sort-an-array/description/