可能有点长，不是最优解

#include<bits/stdc++.h>
using namespace std;
int main(){
	int x,y,b;
	cin>>x>>y;
	
	if(y<=0 || y>12)
	cout<<"no answer";
	
	if(x%400==0)
        b=1;
    else if(x%100==0)
        b=0;
	else if(x%4==0)
        b=1;
	else 
	    b=0;
	
	if(b==1)
	{
		if(y==1 || y==3 || y==5 || y==7 || y==8 || y==10 ||y==12)
		cout<<"31";
		else if(y==4 || y==6 || y==9 || y==11 )
		cout<<"30";
		else if(y==2)
		cout<<"29";
		
	}
	if(b==0)
	{
		if(y==1 || y==3 || y==5 || y==7 || y==8 || y==10 ||y==12)
		cout<<"31";
		else if(y==4 || y==6 || y==9 || y==11 )
		cout<<"30";
		else if(y==2)
		cout<<"28";
		
	}
	return 0;
}

#include<iostream>

using namespace std;

int main()

{

int a,b=0,c;

cin>>a>>c;

if(a%4==0) b=1;//普通闰年

if(a%100==0) b=0;//普通闰年

if(a%400==0) b=1;//世纪闰年，此为重点！！测点一就是测这个

if(c==2){

	if(b==0){

	cout<<"28";	

	}else{

		cout<<"29";

	}

}

if(c==1&&c==3&&c==5&&c==7&&c==8&&c==10&&c==12){

	cout<<"31";

}else{

	if(c!=2){

		cout<<"30";

	}

}

}

#include<iostream> #include<cstdio> #include<iomanip> #include<cmath> using namespace std; int main() { int a,b,c; cin>>a>>b>>c; if(a+b>c){if (c+b>a){if(a+c>b){cout<<"yes"; }else{cout<<"no";} }else{cout<<"no";} }else{cout<<"no";} return 0; }

懒人代码

#include<bits/stdc++.h>
using namespace std;
const int INF=0x3f3f3f3f;
int const N=1e5+10;
int x,y;
int main(){
	cin>>x>>y;
	if(y==2){
		if(x%4==0&&x%100!=0||x%400==0){
			cout<<29;
			return 0;
		}else{
			cout<<28;
			return 0;
		}
	}
	if(y==1||y==3||y==5||y==7||y==8||y==10||y==12)cout<<31;
	else{
		cout<<30;
	}
	return 0;
}

#include <iostream> using namespace std; int main(){ int x,y,b=0; cin>>x>>y; if(x%40) b=1; if(x%1000) b=0; if(x%4000) b=1; if(y2){ if(b0){ cout<<"28"; }else{ cout<<"29"; } } if(y1||y3||y5||y7||y8||y10||y12){ cout<<"31"; }else{ if(y!=2){ cout<<"30"; }

}
return 0;

} //这是绝对AC的代码，并且怎样测试都不会出错（2000年 3月出现的是31）

#include<iostream>
using namespace std;
int main(){
int y=0;
int m=0;
int days[]={ 31,28,31,30,31,30,31,31,30,31,30,31};
while(scanf("%d %d", &y,&m)!=EOF) {
int day=days[m-1];
if((y%40&&y%100!=0)||(y%4000)){
if(m==2){
day++;
}
}
printf("%d\n",day);
}
return 0;
}

#include<stdio.h> #include<iostream> using namespace std; int main() { int x,y; cin>>x>>y; if((x%40&&x%100!=0)||(x%4000)) { if(y2) { cout<<29<<endl; }else if(y1||y3||y5||y7||y8||y12) { cout<<31<<endl; }else { cout<<30<<endl; } }else { if(y2) { cout<<28<<endl; }else if(y1||y3||y5||y7||y8||y12) { cout<<31<<endl; }else { cout<<30<<endl; } } }

#include <stdio.h> #include <iostream> using namespace std; int main() { int y,m; cin >> y >> m; int sum = 0; if(m1||m3||m5||m7||m8||m10||m==12) { sum = 31; } else if(m != 2) { sum = 30; } else { sum = 28; if (y%400 == 0||y%100 != 0 && y%4 == 0) sum += 1; } cout << sum; }

#include<iostream> #include<stdio.h> using namespace std; int main() { int y,m; cin>>y>>m; int sum=0; if(m1||m3||m5||m7||m8||m10||m=12) { sum=31; } else if(m !=2) { sum=30; } else { sum=28; if(y%4000 ||(y%100 !=0 && y%40)) sum+=1; } cout<<sum<<endl; }