Submission

Score: 100

User: 8ii

Problemset: โชว์ของโลมา

Language: cpp

Time: 0.002 second

Submitted On: 2026-03-06 10:56:12

#include <bits/stdc++.h>
using namespace std;

int main() {
    long long n;
    cin >> n;
    if(n == 1){
        cout << 1;
        return 0;
    }
    if(n == 2){
        cout << 7;
        return 0;
    }
    if(n == 3){
        cout << 24;
        return 0;
    }
    long long a = n*2 + n - 2;
    long long sum = 0;
    long long puls = 2 + ((n-3) * 4);
    if(n % 2 == 0){
        for(long long i = 1; i <= n-1; i++){
            if(i % 2 == 0){
                sum += (a+1) % 10;
                a += puls;
                puls -= 8;
            }else{
                sum += a % 10;
            }
        }
        sum += (a-1) % 10;
    }
    else{
        for(long long i = 1; i <= n-2; i++){
            if(i % 2 == 0){
                sum += (a+1) % 10;
                a += puls;
                puls -= 8;
            }
            else{
                sum += a % 10;
            }
        }
        sum += (a+1) % 10;
        sum += (a+2) % 10;
    }
    cout << sum;
}