题解 | #日期累加#

#include<iostream>
#include<cstdio>
using namespace std;
int DayTab[2][13] = {
    {0,31,28,31,30,31,30,31,31,30,31,30,31},
    {0,31,29,31,30,31,30,31,31,30,31,30,31}
};
bool IsLeapYear(int year) {
    return (year % 4 == 0 && year % 10 != 0) || (year % 400 == 0);
}
int YearTab[2] = { 365,366 };
int main() {
    int year, month, day, number;
    int m, num;
    scanf("%d\n", &m);
    while (m--) {
        scanf("%d%d%d%d\n", &year, &month, &day, &number);
        num = 0;
        for (int i = 0; i < month; ++i) {
            num += DayTab[IsLeapYear(year)][i];
        }
        num += day;
        number += num;
        while (number > YearTab[IsLeapYear(year)]) {
            number -= YearTab[IsLeapYear(year)];
            ++year;
        }
        month = 0;
        while (number > DayTab[IsLeapYear(year)][month]) {
            number -= DayTab[IsLeapYear(year)][month];
            ++month;
        }
        day = number;
        cout << year << "-";
        if (month < 10) {
            cout << 0 << month << "-";
        }
        else {
            cout << month << "-";
        }
        if (number < 10) {
            cout << 0 << day << endl;
        }
        else {
            cout << day << endl;
        }
    }
    return 0;
}