Submission

PPPPPP----

Score: 60

User: devilpoohs

Problemset: โชว์ของโลมา

Language: cpp

Time: 0.002 second

Submitted On: 2025-03-23 14:36:59

#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<<7;
        return 0;
    }
    ll num=0;
    // while(n>=0){
    ll nextN=n;

    ll sum=0;
    while(nextN>=2){
        num=num+(nextN*2)+nextN-2;
        // cout<<num<<' ';
        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<<'\n';
    cout<<sum;
        
    return 0;   
}