题解 | 回文日期

#include <stdio.h>
int  ishw(int n){
    int x=n;
    int a=0;
    int sum=0;
while(n>0){
    sum*=10;
    a=n%10;
    sum+=a;
    n/=10;
}
if(sum==x)return 1;
else return 0;
}
int isrun(int n){
    n/=10000;
    if(n%4==0&&n%100!=0||n%400==0)return 1;
    else return 0;
}
int main() {
    int day1,day2;
    scanf("%d\n%d",&day1,&day2);
    int ferun[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
    int run[13]={0,31,29,31,30,31,30,31,31,30,31,30,31};
    int t=day1%100;
    int m=day1%10000/100;
    int count=0;
    while(day1<day2){
        
        day1++;
        if(ishw(day1)){
            count++;
           // printf("%d\n",day1);
        }
        //printf("%d\n",day1);
        if(isrun(day1)){
        if(t==run[m]){
            day1+=100;
            day1/=100;
            day1*=100;
            //printf("%d\n",day1);
            m++;
            t=0;
        }
        }if(isrun(day1)==0){
            if(t==ferun[m]){
                day1+=100;
                day1/=100;
                day1*=100;
                //printf("%d\n",day1);
                m++;
                t=0;
            }
           // printf("%d\n",day1);
        }
        
        
        if(day1/100%100==13){
            //printf("%d\n",day1);
            day1+=10000;
            day1=day1/10000*10000+day1%100;
            day1+=100;
            m=1;
        }t++;
    }
    if(day1==day2){
       if(ishw(day1)==1)count=1;
    }
    printf("%d",count);
    return 0;
}