日期问题

1. 今年的第几天（日期问题）

分析 设置二位数组存储平年和闰年12个月的不同天数，判断输入的年份是平年还是闰年，按照月份逐月累加，最后加上当月天数

#include <cstdio>
using namespace std;
int dayTable[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 % 100 != 0) || (year % 400 == 0);
}
int main(){
    int year, month, day;
    while((scanf("%d %d %d",&year, &month, &day))!= EOF){
        int num = 0;
        for(int i = 0; i < month; ++i)
            num += dayTable[IsLeapYear(year)][i];
        num += day;
        printf("%d", num);
    }
    return 0;
}

2. 已知年份和天数求月日

分析 与上题思路类似

#include <cstdio>
using namespace std;
int dayTable[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 % 100 != 0) || (year % 400 == 0);      //判断是否为闰年
}
int main(){
    int year, month, day, num;
    while((scanf("%d %d",&year, &num))!= EOF){
        int row = IsLeapYear(year);
        month = 0;
        while(num > dayTable[row][month]){ //用num逐月减
          num -= dayTable[row][month];
          month++;
        }
        day = num;
        printf("%04d-%02d-%02d",year,month, day);
    }
    return 0;
}