LeetCode 215. 数组中的第K个最大元素（Kth Largest Element in an Array）

 1 class Solution {
 2 public:
 3     int findKthLargest(vector<int>& nums, int k) {
 4         int idx = quickSort(nums, k, 0, nums.size() - 1);
 5         return nums[idx];
 6     }
 7     int quickSort(vector<int>& nums, int k, int start, int end){
 8         if(start < end){
 9             int p = partition(nums, start, end);
10             cout<<p<<endl;
11             if(p == k - 1) return p;
12             else{
13                 int idx = quickSort(nums, k, start, p - 1);
14                 if(idx == k - 1) return idx;
15                 else return quickSort(nums, k, p + 1, end);
16             }
17         }
18         else return start;
19     }
20     int partition(vector<int>& nums, int start, int end){
21         int i = start - 1;
22         for(int j = start; j < end; j++)
23             if(nums[j] > nums[end]) 
24                 swap(nums[j], nums[++i]);
25         swap(nums[end], nums[++i]);
26         return i;
27     }
28 };