bzoj1857 [Scoi2010]传送带

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
#include<cmath>
#include<map>

using namespace std;

int ax, ay, bx, by, cx, cy, dx, dy, p, q, r;
const double eps = 1e-9;

double dis(double x1, double y1, double x2, double y2)
{
    return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}

double jisuan(double x1, double y1, double x2, double y2)
{
    return dis(ax, ay, x1, y1) / p + dis(x1, y1, x2, y2) / r + dis(x2, y2, dx, dy) / q;
}

double solve(double x, double y)
{
    double lx = cx, ly = cy, rx = dx, ry = dy;
    while (fabs(rx - lx) > eps || fabs(ry - ly) > eps)
    {
        double x1 = lx + (rx - lx) / 3, x2 = lx + (rx - lx) / 3 * 2;
        double y1 = ly + (ry - ly) / 3, y2 = ly + (ry - ly) / 3 * 2;
        if (jisuan(x, y, x1, y1) > jisuan(x, y, x2, y2))
        {
            lx = x1;
            ly = y1;
        }
        else
        {
            rx = x2;
            ry = y2;
        }
    }
    return jisuan(x, y, lx, ly);
}

int main()
{
    scanf("%d%d%d%d%d%d%d%d%d%d%d", &ax, &ay, &bx, &by, &cx, &cy, &dx, &dy, &p, &q, &r);
    double lx = ax, ly = ay, rx = bx, ry = by;
    while (fabs(rx - lx) > eps || fabs(ry - ly) > eps)
    {
        double x1 = lx + (rx - lx) / 3, x2 = lx + (rx - lx) / 3 * 2;
        double y1 = ly + (ry - ly) / 3, y2 = ly + (ry - ly) / 3 * 2;
        if (solve(x1, y1) > solve(x2, y2))
        {
            lx = x1;
            ly = y1;
        }
        else
        {
            rx = x2;
            ry = y2;
        }
    }
    printf("%.2lf\n", solve(lx, ly));
return 0;
}