AcWing 1341. 十三号星期五

原题链接

考察:模拟

思路一:

           枚举每一年的每一月,看该月13号离1900年1月1日有多少天,对天数模7统计.

           这里比较简单的做法是计算xxxx年x月的1日离1900年1月1日有多少天,再+12天就是13号离它多少天.

#include <iostream>
#include <cstdio>
using namespace std;
int month[13] = {0,31,28,31,30,31,30,31,31,30,31,30,31};
int week[8];//W= (d+2*m+3*(m+1)/5+y+y/4-y/100+y/400+1)%7
int main()
{
    int n;
    scanf("%d",&n);
    int days = 0;
    for(int year= 1900;year<1900+n;year++)
    {
        if(year%4==0&&year%100!=0) month[2] = 29;
        if(year%400==0) month[2] = 29;
        for(int m=1;m<=12;m++)
        {
            week[(days+12)%7]++;
            days+=month[m];
        }
        month[2] = 28;
    }
    for(int i=5,j=1;j<=7;i=(i+1)%7,j++) printf("%d ",week[i]);
    printf("\n");
    return 0;
}

思路二:

          听都没听说过的公式法: 基姆拉尔森计算公式

#include <iostream>
#include <cstdio>
using namespace std;
int month[13] = {0,31,28,31,30,31,30,31,31,30,31,30,31};
int week[8];//W= (d+2*m+3*(m+1)/5+y+y/4-y/100+y/400+1)%7
int get(int y,int m,int d)
{
    if(m==1||m==2) y--,m+=12;
    return (d+2*m+3*(m+1)/5+y+y/4-y/100+y/400+1)%7;
}//返回的6代表周六.
int main()
{
    int n;
    scanf("%d",&n);
    int days = 0;
    for(int year= 1900;year<1900+n;year++)
    {
        for(int m=1;m<=12;m++)
            week[get(year,m,13)]++;
    }
    for(int i=6,j=1;j<=7;i=(i+1)%7,j++) printf("%d ",week[i]);
    printf("\n");
    return 0;
}