Kth Largest Element in an Array

Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element.

For example,
Given [3,2,1,5,6,4] and k = 2, return 5.

Note: 

You may assume k is always valid, 1 ≤ k ≤ array's length.

public class Solution {    public int findKthLargest(int[] nums, int k) {        return findKthLargestHelper(nums, k, 0, nums.length - 1);    }        private int findKthLargestHelper(int[] nums, int k, int begin, int end){        if(begin == end && k == 1)            return nums[begin];        int endPoint = begin+1;        int searchEnd = begin+1;        int pivot = nums[begin];        while(searchEnd <= end){            if(nums[searchEnd] > pivot){                swap(nums, searchEnd, endPoint);                searchEnd++;                endPoint++;            }            else{                searchEnd++;            }        }        endPoint--;        swap(nums,endPoint, begin);        if(endPoint - begin + 1 == k)            return pivot;        else if(endPoint - begin + 1 < k){            return findKthLargestHelper(nums, k - (endPoint - begin + 1), endPoint+1, end);        }        else{            return findKthLargestHelper(nums, k, begin, endPoint - 1);        }    }        private void swap(int[] nums, int index1, int index2){        if(index1 == index2)            return;        int tmp = nums[index1];        nums[index1] = nums[index2];        nums[index2] = tmp;    }}