215. Kth Largest Element in an Array

 1 class Solution {
 2 public:
 3     int findKthLargest(vector<int>& nums, int k) {
 4         int sz=nums.size();
 5         int find=sz-k;
 6         int left=0,right=sz-1;
 7         while(1){
 8             int cur=cut(nums, left, right);
 9             if(cur==find)
10                 return nums[cur];
11             else if(cur<find)
12                 left=cur+1;
13             else
14                 right=cur-1;       
15         }
16     }
17     
18     int cut(vector<int>& nums, int start, int end){
19         int temp=nums[start];
20         int left=start;
21         int right=end;
22         while(left!=right){
23             while(left<right&&nums[right]>temp)
24                 --right;
25             while(left<right&&nums[left]<=temp)
26                 ++left;
27             if(left<right)
28                 swap(nums[left], nums[right]);
29         }
30         swap(nums[start], nums[left]);
31         return left;
32     }
33 };