题解 | #日期差值#

#include <iostream>
#include <algorithm>
using namespace std;

class Date {
public:
    Date(int year, int month, int day)
        : _year(year), _month(month), _day(day) {}

    bool operator==(const Date& d) const {
        return _year == d._year && _month == d._month && _day == d._day;
    }


    bool operator<(const Date& d) const {
        if (_year < d._year) return true;
        if (_year == d._year && _month < d._month) return true;
        if (_year == d._year && _month == d._month && _day < d._day) return true;
        return false;
    }

    int GetMonthDay(int year, int month) const {
        static int MonthArr[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
        if (month == 2 && (year % 400 == 0 || (year % 100 != 0 && year % 4 == 0)))
            return 29;
        return MonthArr[month];
    }

    Date& operator--() {
        _day--;
        if (_day == 0) {
            _month--;
            if (_month == 0) {
                _year--;
                _month = 12;
            }
            _day = GetMonthDay(_year, _month);
        }
        return *this;
    }

    bool is_leapyear(int year) const {
        return (year % 400 == 0 || (year % 100 != 0 && year % 4 == 0));
    }

    int operator-(const Date& d) 
     {
        Date max = *this;
        Date min = d;
        if (max < min) {
           max = d;
           min = *this;   
        }

        int count = 0;
        while (!(max._day == 1 && max._month == 1)) {
            --max;
            ++count;
        }

        while (!(min._day == 1 && min._month == 1)) {
            --min;
            --count;
        }

        while (min._year < max._year) {
            count += is_leapyear(min._year) ? 366 : 365;
            ++min._year;
        }

        return abs(count);
    }

private:
    int _year;
    int _month;
    int _day;
};

int main() {
    int year1, month1, day1, year2, month2, day2;
    while (scanf("%4d%2d%2d %4d%2d%2d", &year1, &month1, &day1, &year2, &month2, &day2) != EOF) {
        Date d1(year1, month1, day1);
        Date d2(year2, month2, day2);

        int ret = d1 - d2 +1 ;
        cout << ret << endl;
    }
    return 0;
}