【题解】NC219035 春游（模拟 - 分情况讨论）

https://ac.nowcoder.com/acm/problem/219035

#include <iostream>

using namespace std;
long long typedef LL;

LL fun(LL n, LL a, LL b) {
    if (n <= 2) return min(a, b);
    
    LL ret = 0;
    
    if (a * 3 < b * 2) // 尽可能选择双人船 
    {
        ret += n / 2 * a;
        n %= 2;
        if(n) ret += min(min(a, b), b - a);
    }
    else // 尽可能选择三人船
    {
        ret += n / 3 * b;
        n %= 3;
        if (n == 1) ret += min(min(a, b), 2*a - b);
        else if (n == 2) ret += min(min(a, b), 3*a - b);
    }
    return ret;
}

int main()
{
    int t;
    cin >> t;
    while (t--) {
        LL n, a, b;
        cin >> n >> a >> b;
        cout << fun(n, a, b) << endl;
    }
    
    return 0;
}