简单！其实可以优化

#include <bits/stdc++.h>
using namespace std;
int main(){

int n;
cin >> n;
int d = 1 + n;
int day = d % 7;
// cout << "d, day:" << d << "," << day << endl;
if (day == 1){
    cout << "monday";
} else if (day == 2){
    cout << "tuesday";
} else if (day == 3){
    cout << "wednesday";
} else if (day == 4){
    cout << "thursday";
} else if (day == 5){
    cout << "friday";
} else if (day == 6){
    cout << "saturday";
} else if (day == 0){
    cout << "sunday";
}
    
return 0;

}