Submission

Score: 100

User: Ryuthin94

Problemset: โชว์ของโลมา

Language: cpp

Time: 0.002 second

Submitted On: 2026-03-06 10:08:12

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

int main()
{
    long long n;
    cin >> n;

    long long sum = 0;

    for (long long j = 0; j < n; j++)
    {
        long long k = j / 2;
        long long size_k = n - 2 * k;
        long long start_k = 1 + 4 * k * (n - k);

        long long val;

        if (size_k == 1)
        {
            val = start_k;
        }
        else if (size_k == 2)
        {
            if (j % 2 == 0)
                val = start_k + 3;
            else
                val = start_k + 2;
        }
        else
        {
            if (j % 2 == 0)
                val = start_k + 2 * size_k + (n - 1 - (2 * k + 2));
            else
                val = start_k + 2 * size_k + (size_k - 2);
        }

        sum += val % 10;
    }

    cout << sum;
}