【每日一题12】AcWing 1341. 十三号星期五

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Day12 AcWing 1341. 十三号星期五

思路

  1. 打表/枚举

拓展

  1. 基姆拉尔森计算公式(Kim larsen calculation formula)
  2. 闰年判断 year % 100 && year % 4 == 0 || year % 400 == 0

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  4. AcWing 436. 立体图

代码

按月份枚举
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#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

int month[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};  // 打表
int weekday[7];


int main()
{
    int n;
    cin >> n;

    int days = 0;
    for (int year = 1900; year < 1900 + n; year ++ )
    {
        for (int i = 1; i <= 12; i ++ )
        {
            weekday[(days + 12) % 7] ++ ;
            days += month[i];
            if (i == 2)
            {
                if (year % 100 && year % 4 == 0 || year % 400 == 0)
                    days ++ ;
            }
        }
    }

    for (int i = 5, j = 0; j < 7; i = (i + 1) % 7, j ++ )
        cout << weekday[i] << ' ';
    cout << endl;

    return 0;
}
按天枚举
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#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

int months[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};  // 打表
int weekday[7];

int get(int year, int m)
{
    if (m != 2) return months[m];
    if (year % 100 && year % 4 == 0 || year % 400 == 0)
        return 29;
    return 28;
}

int main()
{
    int n;
    cin >> n;

    int week = 0;
    int year = 1900, month = 1, day = 1;
    while (year < 1900 + n)
    {
        if (day == 13) weekday[week] ++ ;
        week = (week + 1) % 7;
        day ++ ;
        if (get(year, month) < day) month ++, day = 1;
        if (month > 12) month = 1, year ++ ;
    }

    for (int i = 5, j = 0; j < 7; i = (i + 1) % 7, j ++ )
        cout << weekday[i] << ' ';
    cout << endl;

    return 0;
}