poj1434

二分

简单题

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

#define maxn 50005
#define eps 10e-9

struct Cistern
{
    double b, w, h, d;
}cistern[maxn];

double total;
int n;
double v;
double maxh;

int dblcmp(double a, double b)
{
    if (a + eps < b)
        return -1;
    if (a - eps > b)
        return 1;
    return 0;
}

void input()
{
    total = 0;
    maxh = 0;
    scanf("%d", &n);
    for (int i = 0; i < n; i++)
    {
        scanf("%lf%lf%lf%lf", &cistern[i].b, &cistern[i].h, &cistern[i].w, &cistern[i].d);
        total += cistern[i].h * cistern[i].w * cistern[i].d;
        maxh = max(maxh, cistern[i].h + cistern[i].b);
    }
    scanf("%lf", &v);
}

bool high(double h)
{
    total = 0;
    for (int i = 0; i < n; i++)
        if (dblcmp(cistern[i].b, h) <= 0 && dblcmp(cistern[i].b + cistern[i].h, h) >= 0)
            total += (h - cistern[i].b) * cistern[i].w * cistern[i].d;
        else if (dblcmp(cistern[i].b + cistern[i].h, h) <= 0)
            total += cistern[i].h * cistern[i].w * cistern[i].d;
    return dblcmp(total, v) >= 0;
}

double binarysearch()
{
    double l = 0;
    double r = maxh;
    while (dblcmp(l, r) != 0)
    {
        double mid = (l + r) / 2;
        if (high(mid))
            r = mid;
        else
            l = mid;
    }
    return l;
}

int main()
{
    //freopen("t.txt", "r", stdin);
    int t;
    scanf("%d", &t);
    while  (t--)
    {
        input();
        if (total < v)
        {
            printf("OVERFLOW\n");
            continue;
        }
        printf("%.2f\n", binarysearch());
    }
    return 0;
}