1205. By the Underground or by Foot?

http://acm.timus.ru/problem.aspx?space=1&num=1205

spfa

代码：

#include<iostream>

#include<cstdio>

#include<cstring>

#include<string>

#include<vector>

#include<map>

#include<cmath>

#include<queue>

#include<stack>

#include<algorithm>



using namespace std;

const int INF=0x3f3f3f3f;

const int N=205;

double cost[N][N];

struct node

{

    double x,y;

}point[N];

int f[N];

double Fdist(int i,int j)

{

    return sqrt((point[i].x-point[j].x)*(point[i].x-point[j].x)+

                (point[i].y-point[j].y)*(point[i].y-point[j].y));

}

double spfa(int s,int m,int &I)

{

    bool in[N];

    double dist[N];

    for(int i=0;i<=m;++i)

    {in[i]=false;dist[i]=-1.0;}

    queue<int>str;

    str.push(s);

    in[s]=true;

    dist[0]=0.0;

    while(!str.empty())

    {

        int x=str.front();str.pop();//cout<<x<<" "<<dist[x]<<endl;

        in[x]=false;

        for(int i=0;i<=m;++i)

        {

            if(i!=x&&(dist[i]<0.0||dist[i]>dist[x]+cost[x][i]))

            {

                dist[i]=dist[x]+cost[x][i];

                f[i]=x;

                if(!in[i])

                {

                    in[i]=true;

                    str.push(i);

                }

            }

        }

    }

    int k=f[m];

    I=0;

    while(k!=0)

    {

        ++I;

        k=f[k];

    }

    return dist[m];

}

void dfs(int x)

{

    if(f[x]!=0)

    dfs(f[x]);

    printf(" %d",x);

}

int main()

{

    //freopen("data.txt","r",stdin);

    double fv,uv;

    int n;

    while(scanf("%lf %lf",&fv,&uv)!=EOF)

    {

       scanf("%d",&n);

       for(int i=0;i<=n+1;i++)

       cost[i][i]=0.0;

       for(int i=1;i<=n;++i)

       {

           scanf("%lf %lf",&point[i].x,&point[i].y);

           for(int j=1;j<i;++j)

           {

               cost[i][j]=cost[j][i]=Fdist(i,j)/fv;

           }

       }

        int l1,l2;

        while(scanf("%d %d",&l1,&l2))

        {

            if(l1==0&&l2==0)

            break;

            cost[l1][l2]=cost[l2][l1]=min(cost[l1][l2],Fdist(l1,l2)/uv);

        }

        scanf("%lf %lf",&point[0].x,&point[0].y);

        scanf("%lf %lf",&point[n+1].x,&point[n+1].y);

        for(int i=0;i<=n+1;++i)

        {cost[i][0]=cost[0][i]=Fdist(0,i)/fv;cost[n+1][i]=cost[i][n+1]=Fdist(n+1,i)/fv;}

        int I;

        printf("%.6lf\n",spfa(0,n+1,I));

        printf("%d",I);

        if(I)

        dfs(f[n+1]);

        printf("\n");

    }

    return 0;

}