215. Kth Largest Element in an Array

class Solution {private:    void swap(vector<int>&nums,int i,int j)    {        int temp=nums[i];        nums[i]=nums[j];        nums[j]=temp;    }    int quickSelect(vector<int>&nums,int l,int r,int k)    {        int temp=nums[r];        int i=l,j=r;        while(i<j)        {           while(i<j&&nums[i]<=temp)                i++;            if(i<j)                swap(nums,i,j);            while(i<j&&nums[j]>=temp)                j--;            if(i<j)                swap(nums,i,j);        }        nums[i]=temp;        int m=i-l+1;        if(k==m)            return i;        else if(k>m)            return quickSelect(nums,i+1,r,k-m);        else             return quickSelect(nums,l,i-1,k);    }public:    int findKthLargest(vector<int>& nums, int k) {        int p=quickSelect(nums,0,nums.size()-1,nums.size()-k+1);        return nums[p];    }};