1867: John and Health rate

Description

The cold and flu season is here.John is worried about his cow. In order to monitor the situation of his cow,he do some inspecting everyday,and record the “health rate” for each cow.The “health rate” is a integer which can show the cow’s health condition.The higher a cow’s health rate is ,the healthier the cow is.What’s more,the doctor told John that the k-th small health rate is dangerous.Because the doctor thought there are at most k healthy cows. So John has to find out which number is the k-th small.Can you help him?

Input

Input contains multiple test cases.
The first line contains two integers n,k (1?≤?n?≤?1000000,1<=k<=n) — the number of cows and dangerous number. The second line contains n integers,and the i-th integer ai(-10000<=ai<=10000) is the i-th cow’s health rate

Output

Output a single line with the k-th small health rate.

Sample Input

2 1
3 2
5 2
-1 0 -2 5 3

Sample Output

2
-1



其实很简单，就用一个sort就可以解决，时间复杂度为O(nlogn）,最小的时间复杂度要用到桶排序？

#include <iostream>
#include<cstdio>
#include<algorithm>
using namespace std;

int n,k,a[1000000];

int main()
{
    while(~scanf("%d%d",&n,&k)){
        for(int i=0;i<n;i++)
            scanf("%d",&a[i]);
        sort(a,a+n);
         printf("%d\n",a[k-1]);
    }
    return 0;
}