题解 | Day of Week

#include <iostream>
#include <string>
#include <vector>
using namespace std;

vector<string> weekdays={"Monday","Tuesday","Wednesday","Thursday","Friday","Saturday","Sunday"};

vector<string> Months={" ","January","February","March","April","May","June","July","August","September","October","November","December"};

vector<vector<int>> a = {
    {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 yr){
    return ((yr%4==0&&yr%100!=0)||yr%400==0)?true:false;
}

int daystofirst(int year,int month,int day){
    int count=0;
    int year1=1;
    while(year>year1){
        count+=(isLeapyear(year1)?366:365);
        year1++;
    }
    for(int i=1;i<month;i++){
        count+=(isLeapyear(year)?a[1][i]:a[0][i]);
    }
    count+=day;
    count--;
    return count;
}

int findIndex(string month){
    int idx = -1;
    for (int i = 0; i < Months.size(); i++) {
    if (Months[i] == month) {
        idx = i;
        break;
    }
}
    return idx;
}


int main() {
    int day,year;
    string month;
    while(cin>>day>>month>>year){
        int idx = findIndex(month);
        int days = daystofirst(year, idx, day);
        int weekdayindex = days%7;
        cout<<weekdays[weekdayindex]<<endl;
    }
    return 0;
}