Submission

PPPPPP----

Score: 60

User: Punnawith

Problemset: โชว์ของโลมา

Language: cpp

Time: 0.002 second

Submitted On: 2025-03-23 14:54:09

#include <bits/stdc++.h>

using namespace std;
#define ll long long int
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n;
    cin >> n;

    if(n == 1) {
        cout << 1;
        return 0;
    }
    if(n == 2) {
        cout << 2;
        return 0;
    }

    ll num = 0;
    ll nextN = n;
    ll sum = 0;

    while(nextN >= 2) {
        num = num + (nextN * 2) - 2 + nextN;

        if(num == n * n) {
            sum += ((num % 10) + ((num - 1) % 10));
        } else {
            sum += ((num % 10) + ((num + 1) % 10));
        }

        num += nextN - 2;
        nextN -= 2;
    }
    if(n % 2 == 1) {
        sum += (n * n) % 10;
    }

    cout << sum;
}