先贴个题目：
以及原题链接：1229. 日期问题 - AcWing题库
https://www.acwing.com/problem/content/1231/
这题其实和之前的回文日期相似，可以直接暴力枚举，然后得解，放个小片段：
for (int date = 19600101; date <= 20591231; date ++ ){int year = date / 10000, month = date % 10000 / 100, day = date % 100;if (check_valid(year, month, day)){if (year % 100 == a && month == b && day == c || month == a && day == b && year % 100 == c || day == a && month == b &&year % 100 == c) printf("%d-%02d-%02d\n", year, month, day);}}
然后我觉得计算不够方便，次数有点多，优化！其实这个题可以简化成纯暴力枚举判断是否合法，给大家看看我的原码：
#include <iostream>
#include <algorithm>
#include<cstring>
using namespace std;struct Date
{int year, month, day;
};bool operator<(Date &a, Date &b)
{if (a.year < b.year)return true;else if (a.year == b.year){if (a.month < b.month)return true;else if (a.month == b.month){if (a.day < b.day)return true;elsereturn false;}elsereturn false;}elsereturn false;
}Date date[20];
bool legal[20];
int a[3], days[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};bool check(int year)
{if (year % 400 == 0 || year % 100 != 0 && year % 4 == 0)return true;elsereturn false;
}
int main()
{memset(legal, true, sizeof(legal));int cnt = 0;scanf("%d/%d/%d", &a[0], &a[1], &a[2]);for (int i = 0; i < 3; ++i)for (int j = 0; j < 3; ++j)for (int k = 0; k < 3; ++k){int year = a[i], month = a[j], day = a[k];if (i == j || j == k || i == k || i == 1 || j == 2)continue;if (year >= 60)year += 1900;elseyear += 2000;if (month < 1 || month > 12)continue;if (month != 2)if (day < 1 || day > days[month])continue;if (month == 2 && check(year) == true)if (day < 1 || day > 29)continue;if (month == 2 && check(year) == false)if (day < 1 || day > 28)continue;date[cnt].year = year;date[cnt].month = month;date[cnt].day = day;cnt++;}sort(date, date + cnt);for (int i = 0; i < cnt - 1; ++i){if (date[i].year == date[i + 1].year && date[i].month == date[i + 1].month && date[i].day == date[i + 1].day)legal[i] = false;}for (int i = 0; i < cnt; ++i)if (legal[i])printf("%d-%02d-%02d\n", date[i].year, date[i].month, date[i].day);return 0;
}其实代码会稍微比纯暴力枚举长很多，但确实计算速度快，由于要按时间先后输出，创建结构体数组以及重载<和sort实现排序功能。以及注意不是每个位置的数都可以表示日月年，所以判断条件较为复杂。但yysy，写出来的感觉挺爽的（）。
by———2024.2.28刷题记录
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