题解 | 网购

#include <stdio.h>

int main() {
    float money, val;
    int arr[3] = {0};
    scanf("%f", &money);
    for (int i = 0; i < 3; i++) {
        scanf("%d", &arr[i]);
    }
    if (arr[0] == 11) {
        if (arr[2] == 1) {
            val = money * 0.7 - 50;
        } else {
            val = money * 0.7;
        }
    } else {
        if (arr[2] == 1) {
            val = money * 0.8 - 50;
        } else {
            val = money * 0.8;
        }
    }
    if (val < 0)val = 0;
    printf("%.2f", val);
    return 0;
}