C. Less or Equal1200 / 排序 思维

Posted 2023-02-19 幽殇默

https://codeforces.com/problemset/problem/977/C

#include<bits/stdc++.h>
using namespace std;
const int N=1e5*2+10;
int a[N],n,k;
int main(void)

	cin>>n>>k;
	for(int i=1;i<=n;i++) cin>>a[i];
	sort(a+1,a+n+1);
	bool flag=true;
	if(k>n) flag=false;
	if(k+1<=n&&a[k]==a[k+1]) flag=false;
	if(flag) 
	
		if(k) cout<<a[k];
		else//k==0
		
			int ans=a[1]-1;
			if(ans==0) puts("-1");
			else cout<<ans;
		
	
	else cout<<-1;
	return 0;