题解 | #日期差值#

#include <cmath>
#include <cstdio>
#include <iostream>
#include <algorithm>
using namespace std;
int month[2][13] = {
    {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},//平年
    {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}//闰年
};
int sum[2][12];
bool judge(int y) {
    if (y % 400 == 0 || y % 100 != 0 && y % 4 == 0) return true;
    return false;
}
int getDays(int y, int m, int d) {//获取在该年的第几天
    if (judge(y)) return sum[1][m - 1] + d;
    return sum[0][m - 1] + d;
}
int main() {
    for (int i = 1; i <= 12; i++) {
        sum[0][i] = sum[0][i - 1] + month[0][i];//平年
        sum[1][i] = sum[1][i - 1] + month[1][i];//闰年
    }
    int y1, m1, d1, y2, m2, d2;
    while (scanf("%4d%2d%2d", &y1, &m1, &d1) != EOF) {
        scanf("%4d%2d%2d", &y2, &m2, &d2);
        int res = 0;
        if (y1 < y2) {
            res = getDays(y2, m2, d2) - getDays(y1, m1, d1);
            for (int i = y1; i < y2; i ++) {
                res += 365;
                if (judge(i)) res += 1; //闰年多一天
            }
        } else if (y1 == y2) {
            res = fabs(getDays(y2, m2, d2) - getDays(y1, m1, d1));
        } else {
            res = getDays(y1, m1, d1) - getDays(y2, m2, d2);
            for (int i = y2; i < y1; i ++) {
                res += 365;
                if (judge(i)) res += 1; //闰年多一天
            }
        }
        cout << res + 1 << endl;
    }
    return 0;
}