题解 | 清楚姐姐买竹鼠

#include <stdio.h>

int main() {
    long long int a, b, x, n = 0, m = 0, price = 0;
    scanf("%lld %lld %lld", &a, &b, &x);
    if (x < 3) {
        price = x * a;
        printf("%lld", price);
    } else if (x >= 3) {
        if (b < a * 3) {
            if (b < a) {
                n = x % 3;
                m = x / 3;
                price = b * m + n * b;
                printf("%lld", price);
            }
            if (b >= a) {
                n = x % 3;
                m = x / 3;
                price = b * m + n * a;
                printf("%lld", price);
            }

        } else if (b > a * 3) {
            price = a * x;
            printf("%lld", price);
        }
    }

    return 0;
}