python/TangDou/CSP-J/BiShuaTi/meiju/P2010_int.cpp

// https://www.luogu.com.cn/problem/P2010
#include <bits/stdc++.h>

using namespace std;

//月份日期常数数组
int months[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

//判断是不是闰年
bool LeapYear(int year) {
    return ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0);
}
//是不是回文字符串
bool isHW(string s) {
    string t = s;
    reverse(t.begin(), t.end());
    return s == t;
}

int cnt;
int main() {
    int st, ed;
    cin >> st >> ed;

    int y1 = st / 10000;
    int y2 = ed / 10000;

    //枚举年份
    for (int i = y1; i <= y2; i++)
        // 枚举月份
        for (int j = 1; j <= 12; j++) {
            //枚举日期
            int day = months[j];
            if (LeapYear(i) && j == 2) day = 29; //闰年二月份，共29天
            for (int k = 1; k <= day; k++) {
                int s = i * 10000 + j * 100 + k;
                //与范围字符串st,ed进行比较，如果不在范围内，continue
                if (s < st || s > ed) continue; //日期字符串符合字典序
                //判断是不是回文
                char x[10];
                sprintf(x, "%d", s);
                if (isHW(x)) cnt++;
            }
        }
    //输出
    printf("%d\n", cnt);
    return 0;
}