hdu 1596 find the safest road (最短路)

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/*floyd直接水过*/#include<cstdio>#include<cstring>#include<iostream>#define N 1001using namespace std;int n,x,y;double road[N][N],t;int main(){    while(scanf("%d",&n)!=EOF)    {        memset(road,0,sizeof(road));        for(int i=1;i<=n;i++)        {            for(int j=1;j<=n;j++)            {                scanf("%lf",&t);                if(t>road[i][j])                {                    road[i][j]=t;                    road[j][i]=t;                }            }        }        for(int k=1;k<=n;k++)        {            for(int i=1;i<=n;i++)            {                if(road[i][k])                for(int j=1;j<=n;j++)                {                    if(road[i][j]<road[i][k]*road[k][j])                    {                        road[i][j]=road[i][k]*road[k][j];                    }                }            }        }        scanf("%d",&n);        for(int i=1;i<=n;i++)        {            scanf("%d%d",&x,&y);            if(road[x][y]!=0)            printf("%.3lf\n",road[x][y]);            else            printf("What a pity!\n");        }    }}/*spfa*/#include<iostream>#include<cstring>#include<cstdio>#include<queue>using namespace std;double map[1001][1001],dis[1001];int visit[1001],s,e,n;void SPFA(int s){    int p,i;    queue<int> qu;    qu.push(s);    visit[s]=1;    dis[s]=1;    while(!qu.empty())    {        p=qu.front();        qu.pop();        visit[p]=0;        for(i=1;i<=n;i++)        {            if(map[p][i]==0||p==i)                continue;            if(dis[p]*map[p][i]>dis[i])            {                dis[i]=dis[p]*map[p][i];                if(visit[i]==0)                {                    visit[i]=1;                    qu.push(i);                }            }        }    }}int main(){    freopen("test.txt","r",stdin);    int i,j,m;    while(scanf("%d",&n)!=EOF)    {        for(i=1;i<=n;i++)        {            for(j=1;j<=n;j++)            {                scanf("%lf",&map[i][j]);            }        }        scanf("%d",&m);        while(m--)        {            scanf("%d%d",&s,&e);            for(i=1;i<=n;i++)            {                visit[i]=0;                dis[i]=0;            }            SPFA(s);            if(dis[e]!=0)            printf("%.3lf\n",dis[e]);            else            puts("What a pity!");        }    }    return 0;}