Diary_3.1

codeforces

1. The Play Never Ends

void solve(){
    int n;  cin >> n;
    if(n%3 == 1){
        cout << "YES" << endl;
    }else{
        cout << "NO" << endl;
    }
}

2. Perfecto

void solve(){
    int n;  cin >> n;
    int last = n*(n+1)/2;
    int ls = sqrt(last);
    if(last == ls*ls){
        cout << -1 << endl;
        return;
    }
    int a[n+1];
    for(int i=1; i<=n; i++){
        a[i] = i;
    }
    a[1] = 2, a[2] = 1;
    for(int i=3; i<=n; i++){
        int cc = i*(i+1)/2;
        int c = sqrt(cc);
        if(c*c == cc){
            swap(a[i], a[i+1]);
        }
    }
    for(int i=1; i<=n; i++){
        cout << a[i] << ' ';
    }
    cout << endl;
}

不开 long long 钉耻辱柱上！！！！！！！！！！！