迷阵突围(dij)

迷阵突围

#include<iostream>
#include<cstdio>
#include<vector>
#include<cmath>
#include<string.h>
#include<map>
using namespace std;
const int MAXN=205;
double inf=99999999;
struct po
{
    int x, y;
} p[MAXN];

int fa[MAXN];

struct node
{
    int no;
    double weight;
    node(int noo,double wgt)
    {
        no=noo;
        weight=wgt;
    }
};

double dis[MAXN];
int n;
bool mark[MAXN];
vector<node>ve[MAXN];

void dij(int left,int right)
{
    int now = 1;
    dis[now]=0;
    memset(mark,false,sizeof(mark));
    mark[now]=true;
    for(int i=2; i<=n; i++)
        dis[i]=inf;

    for(int i=1; i<n; i++)
    {
        for(int j=0; j<ve[now].size(); ++j)
        {
            if(mark[ve[now][j].no] || (now==left&&ve[now][j].no==right) || (now==right&&ve[now][j].no==left))
                continue;

            if(dis[ve[now][j].no]>dis[now]+ve[now][j].weight)
            {
                if(!right&&!left)fa[ve[now][j].no]=now;
                dis[ve[now][j].no]=dis[now]+ve[now][j].weight;
            }
        }

        int mn=inf;
        for(int i=1; i<=n; i++)
        {
            if(mark[i])
                continue;

            if(dis[i]<mn)
            {
                mn=dis[i];
                now=i;
            }
        }

        mark[now]=true;
    }
}

int main()
{
    int m;
    cin >> n >> m;
    memset(mark,false,sizeof(mark));
    for(int i = 1; i <= n; i++)
    {
        int ip1,ip2;
        cin >> ip1 >> ip2;
        p[i].x = ip1;
        p[i].y = ip2;
    }

    for(int i = 1; i <= m; i++)
    {
        int ip1,ip2;
        cin >> ip1 >> ip2;
        double len = sqrt((p[ip1].x-p[ip2].x)*(p[ip1].x-p[ip2].x)+(p[ip1].y-p[ip2].y)*(p[ip1].y-p[ip2].y));
        ve[ip1].push_back(node(ip2,len));
        ve[ip2].push_back(node(ip1,len));
    }

    dij(0,0);
    if(dis[n]==inf)
    {
        cout<<"-1"<<endl;
        return 0;
    }

    double mn = inf;
    int now = n;
    fa[1] = 0;
    while(fa[now])//去掉第1次找到最短路径中的每条边
    {
        dij(fa[now],now);
        mn = min(dis[n],mn);
        now = fa[now];
    }

    if(mn == inf)
        cout<<"-1"<<endl;
    else
        printf("%.2lf",mn);

    return 0;
}