Java快排切分

import java.util.*;
public class Solution {
    ArrayList<Integer> result = new ArrayList<>();
    public ArrayList<Integer> GetLeastNumbers_Solution(int [] input, int k) {
        if(k == 0 || k >input.length) {
            return result;
        }
        quickSearch(input, 0, input.length - 1, k - 1);
        return result;
    }

    void quickSearch(int[] nums, int left, int right, int k) {
        int index = partition(nums, left, right);
        if (index == k) {
            for (int i = 0; i <=k; i++) {
                result.add(nums[i]);
            }
        }else if (index > k) {
            quickSearch(nums, left, index - 1, k);
        } else {
            quickSearch(nums, index + 1, right, k);
        }
    }

    int partition(int[]nums, int left, int right) {
        int value = nums[left];
        int index = left;
        for (int i = left; i <= right; i++) {
            if (nums[i] < value) {
                index++;
                swap(nums, i, index);
            }
        }
        swap(nums, index, left);
        return index;
    }

    void swap(int[] nums, int left, int right) {
        int temp = nums[left];
        nums[left] = nums[right];
        nums[right] = temp;
    }
}