AcWing每日一题--十三号星期五

https://www.acwing.com/problem/content/1343/

按天枚举

#include<iostream>
using namespace std;
int months[]={0,31,28,31,30,31,30,31,31,30,31,30,31};
int weekend[7];
int get(int y,int m){
    if(m!=2) return months[m];
    else{
        if(y%100!=0&&y%4==0||y%400==0){
            return 29;
        }
        return 28;
    }
}
int main(void){
    int n;
    cin>>n;
    int days=0;
    int year=1900,month=1,day=1;
    while(year<1900+n){
        if(day==13){
            weekend[days%7]++;
        }
        days++;
        day++;
        if(day>get(year,month)) day=1,month++;
        if(month>12) month=1,year++;
    }
    for(int i=5,j=0;j<7;i=(i+1)%7,j++){
        cout<<weekend[i]<<" ";
    }
    return 0;
}

按月枚举

#include<iostream>
using namespace std;
int months[]={0,31,28,31,30,31,30,31,31,30,31,30,31};
int weekend[7];
int main(void){
    int n;
    cin>>n;
    int days=0;
    for(int year=1900;year<1900+n;year++){
        for(int month=1;month<=12;month++){
            weekend[(days+12)%7]++;
            days+=months[month];
            if(month==2){
                if(year%100!=0&&year%4==0||year%400==0){
                    days++;
                }
            }
        }
    }
    for(int i=5,j=0;j<7;i=(i+1)%7,j++){
        cout<<weekend[i]<<" ";
    }
    return 0;
}