201903

小中大

#include<bits/stdc++.h>
using namespace std;
int a[100010];
const int inf=0x3f3f3f3f;
int main()
{
	int n;cin>>n;
	for(int i=1;i<=n;i++) cin>>a[i];
	sort(a+1,a+1+n);
	printf("%d ",a[n]);
	if(n%2==0)
	{
		if((a[n/2]+a[n/2+1])%2==1)
		{
			printf("%.1f ",(a[n/2]+a[n/2+1])/2.0);
		}else{
			printf("%d ",(a[n/2]+a[n/2+1])/2);
		}
	}else{
		printf("%d ",(a[n/2+1]));
	}
	printf("%d
",a[1]);
	
}

二十四点
(http://118.190.20.162/view.page?gpid=T88)

#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;cin>>n;
	while(n--)
	{
		string s;cin>>s;
		stack<int>q;
		stack<char>op;
		for(int i=0;i<s.size();i++)
		{
			if(isdigit(s[i])) q.push(s[i]-'0');
			else if(s[i]=='-') {
				q.push(-1*(s[i+1]-'0'));
				op.push('+');
				i++;
			}
			else if(s[i]=='/')
			{
				int top=q.top();q.pop();
				q.push(top/(s[i+1]-'0'));
				i++;
			}
			else if(s[i]=='x'){
				int top=q.top();q.pop();
				q.push(top*(s[i+1]-'0'));
				i++;
			}
			else op.push(s[i]);
		}
//		while(!op.empty())
//		{
//			cout<<op.top()<<" ";op.pop();
//		}
		while(q.size()>1)
		{
			int x=q.top();q.pop();
			int y=q.top();q.pop();
			if(op.top()=='+') q.push(x+y);
			if(op.top()=='x') q.push(x*y);
			if(op.top()=='/') q.push(y/x);
//			printf("%d%c%d=%d
",y,op.top(),x,q.top());
			op.pop();
		}
		if(q.top()==24)
		{
			puts("Yes");
		}else{
			puts("No");
		}
	}
}
/*
10
9+3+4x3
5+4x5x5
7-9-9+8 
5x6/5x4
3+5+7+9
1x1+9-9
1x9-5/9
8/5+6x9
6x7-3x6
6x4+4/5
*/