466. 回文日期

闰年判断：y % 4 == 0 && y % 100 || y % 400 == 0

#include<iostream>
using namespace std;

int days[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

int check(int date){
    int p = 1e7, q = 10;
    while(p >= q){
        int a = date / p % 10, b = date % q / (q / 10);
        if(a != b) return 0;
        p /= 10, q *= 10;
    } 
    return 1;
}

int main(){
    int date1, date2;
    
    cin >> date1 >> date2;
    
    int y = date1 / 10000, m = date1 % 10000 / 100, d = date1 % 100;
    
    int res = 0;
    
    while(date1 <= date2){
        if(check(date1)) res ++;
        d ++;
        int t = days[m];
        if(m == 2 && (y % 4 == 0 && y % 100 || y % 400 == 0)) t ++;
        if(d > t) d = 1, m ++;
        if(m > 12) m = 1, y ++;
        date1 = y * 10000 + m * 100 + d; 
    }
    
    cout << res;
    return 0;   
}