*Kth Largest Element in an Array

public class Solution {
public int findKthLargest(int[] nums, int k) {
    if (k < 1 || nums == null) {
        return 0;
    }
 
    return getKth(nums.length - k +1, nums, 0, nums.length - 1);
}
 
public int getKth(int k, int[] nums, int start, int end) {
 
    int pivot = nums[end];//如果改成start就不对。如何ramdon pivot
//    System.out.println(pivot);
 
    int left = start;
    int right = end;
 
    while (true) {
 
        while (nums[left] < pivot && left < right) {
            left++;
        }
 
        while (nums[right] >= pivot && right > left) {
            right--;
        }
 
        if (left == right) {
            break;
        }

        swap(nums, left, right);
    }
 
    swap(nums, left, end);  //??
 
    if (k == left + 1) {
        return pivot;
    } else if (k < left + 1) {
        return getKth(k, nums, start, left - 1);
    } else {
        return getKth(k, nums, left + 1, end);
    }
}
 
public void swap(int[] nums, int n1, int n2) {
    int tmp = nums[n1];
    nums[n1] = nums[n2];
    nums[n2] = tmp;
}
}