力扣面试题40 最小的k个数

class Solution {
public:
    void quickSort(vector<int>& arr, int left, int right, int k)
    {
        if (left >= right || k < left || k > right)
            return;
        int l = left, r = right, pivot = arr[left];

        while (l <= r)
        {
            while (l <= right && arr[l] <= pivot)l++;
            while (left <= r && arr[r] > pivot)r--;
            if (l < r)
            {
                int temp = arr[l];
                arr[l++] = arr[r];
                arr[r--] = temp;
            }
        }
        if (l > r)
            l--;
        arr[left] = arr[l];
        arr[l] = pivot;
        if (k <= l)
        {
            quickSort(arr, left, l - 1, k);
        }
        else
        {
            quickSort(arr, l + 1, right, k);
        }
    }
    
    vector<int> getLeastNumbers(vector<int>& arr, int k)
    {
        quickSort(arr, 0, arr.size() - 1, k);
    
        vector<int> v;
        v.assign(arr.begin(), arr.begin() + k);
        return v;
    }

};