luoguP1354房间最短路问题

判断两点间连通性，建图跑floyed

#include<bits/stdc++.h>
using namespace std;
const int N=105;
struct node
{
    double z[5],x;
}q[N];double e[N][N];
double dis(double x1,double y1,double x2,double y2)
{
    return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
}
bool come(int i,int j,int a,int b)
{
    if(j-i<2)return 0;
    double x1=q[i].x,x2=q[j].x,y1=q[i].z[a],y2=q[j].z[b];if(x1==x2)return 1;
    double k=(y1-y2)/(x1-x2),bb=y1-x1*k;
    for(i=i+1;i<j;++i)
    {
        double y=q[i].x*k+bb;
        if(y<q[i].z[1]||(y>q[i].z[2]&&y<q[i].z[3])||y>q[i].z[4])return 1;
    }
    return 0;
}
void add(int i,int j,int a,int b)
{
    if(come(i,j,a,b))return;
    e[i*4+a][j*4+b]=e[j*4+b][i*4+a]=dis(q[i].x,q[i].z[a],q[j].x,q[j].z[b]);
}
int main()
{
    int n;
    scanf("%d",&n);
    for(int i=1;i<=n;++i)
    {
        scanf("%lf",&q[i].x);
        for(int j=1;j<=4;++j)scanf("%lf",&q[i].z[j]);
    }
    q[0].x=0;q[++n].x=10;
    for(int i=1;i<=4;++i)q[0].z[i]=q[n].z[i]=5;
    for(int i=1;i<=n*4+4;++i)for(int j=1;j<=n*4+4;++j)e[i][j]=1e9;
    
    for(int i=0;i<=n;++i)
    for(int j=i+1;j<=n;++j)
    for(int a=1;a<=4;++a)
    for(int b=1;b<=4;++b)
    add(i,j,a,b);
    for(int k=1;k<=n*4+4;++k)
    for(int i=1;i<=n*4+4;++i)
    for(int j=1;j<=n*4+4;++j)
    e[i][j]=min(e[i][j],e[i][k]+e[k][j]);
    printf("%.2lf",e[1][n*4+1]);
    return 0;
}