**[Lintcode]Kth Largest Element

Find K-th largest element in an array.

 Notice

You can swap elements in the array

Have you met this question in a real interview? 

Yes

Example

In array [9,3,2,4,8], the 3rd largest element is 4.

In array [1,2,3,4,5], the 1st largest element is 5, 2nd largest element is 4, 3rd largest element is 3 and etc.

空间复杂度为O（1），时间复杂度为O（n）。使用快速排序法。

class Solution {
 /*
 * @param k : description of k
 * @param nums : array of nums
 * @return: description of return
 */
 public int kthLargestElement(int k, int[] nums) {
     int left = 0, right = nums.length - 1;
     
     while(left < right) {
         int l = left, r = right;
         int key = nums[l];
         while(l < r) {
             while(l < r && nums[r] < key) r--;
             nums[l] = nums[r];
             while(l < r && nums[l] >= key) l++;
             nums[r] = nums[l];
         }
        nums[l] = key;
         
         if(l == k - 1) return nums[l];
         else if(l < k - 1) left = l + 1;
         else right = l - 1;
     }
     return nums[k - 1];
 }
};