这种题的本质就是单纯的顺序检索题，这个代码还可以优化，就是不用day，直接在else情况下break，此时输出为year，month，n，注意输出的格式 

#include <bits/stdc++.h>
using namespace std;

int isLeap(int year){
	if(year%400==0||(year%4==0&&year%100!=0)){
		return 1;
	}else return 0;
}

int main(){
	int year,n;
	int monthdata[2][13]={{0,31,28,31,30,31,30,31,31,30,31,30,31},
						  {0,31,29,31,30,31,30,31,31,30,31,30,31}};
	while(scanf("%d %d",&year,&n)!=EOF){
		int a=isLeap(year);
		int month=1;int day=0;
		for(int i=1;i<13;i++){
			if(n>monthdata[a][i]){
				n-=monthdata[a][i];
				month++;
			}else{
				day=n;
				break;
			}
		}
		printf("%04d-%02d-%02d\n",year,month,day);
	}
	return 0;
}