UVA 12230 Crossing Rivers——期望

期望简单题，易知期望过河时间为2l/v，然后加上d-sum（L）即可

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
int main() {
    //freopen("out.txt", "w", stdout);
    int kase = 0, n, d;
    while (~scanf("%d %d", &n, &d) && (n+d)) {
        int sum = 0, p, l, v;
        double ans = 0;
        while (n--) {
            scanf("%d %d %d", &p, &l, &v);
            ans += 2.0 * l / v;
            sum += l;
        }
        printf("Case %d: %.3lf\n\n", ++kase, ans + d - sum);
    }
    return 0;
}