#include <iostream>
using namespace std;
int ans = 0 , k;
void findkth(int a[] , int l , int r){
    if(l == r){
        ans = a[l];
        return;
    }
    int i = l , j = r , flag = a[(l + r) / 2] , tmp;
    do{
        while(a[i] < flag) i++;
        while(a[j] > flag) j--;
        if(i <= j){
            tmp = a[i];
            a[i] = a[j];
            a[j] = tmp;
            i++;
            j--;
        }
    }while(i <= j);
    if(k <= j)findkth(a, l, j);
    else if(k <= i)findkth(a, i, r);
    else findkth(a , j + 1 , i - 1);
}
int main (){
    int n;
    cin >> n >> k;
    int a[n];
    for(int i = 0;i < n;i++)
        cin >> a[i];
    findkth(a, 0, n - 1);
    cout << ans << endl;
    return 0;
}

如果能优化的话送关注