UVA 10491 Cows and Cars——概率水题

#include <cstdio>
#include <cstring>
using namespace std;
int main() {
    int a, b, c;
    while (scanf("%d %d %d", &a, &b, &c) == 3) {
        double ans1 = 1.0 * b / (1.0 * a + b) * 1.0 * (b - 1) / (1.0 * a - c + b - 1);
        double ans2 = 1.0 * a / (1.0 * a + b) * 1.0 * b / (1.0 * a - c + b - 1);
        printf("%.5lf\n", ans1 + ans2);
    }
    return 0;
}