【LightOJ 1002】 Country Roads

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【LightOJ 1002】 Country Roads

。。。又一个另类OJ。。。最长路贴个SPFA的

#include <iostream>#include <cstdio>#include <cstdlib>#include <cstring>#include <queue>#include <set>using namespace std;int mp[555][555];int dis[555];bool vis[555];int n,m,tp,s;void SPFA(){    memset(vis,0,sizeof(vis));    memset(dis,-1,sizeof(dis));    vis[s] = 1;    queue <int> q;    q.push(s);    vis[s] = 1;    dis[s] = 0;    int u,v,w,i,k;    while(!q.empty())    {        u = q.front();        q.pop();        vis[u] = 0;        for(i = 0; i < n; ++i)        {            if(mp[u][i] == -1) continue;            k = dis[i];            if(dis[i] == -1) dis[i] = max(mp[u][i],dis[u]);            else  dis[i] = min(dis[i],max(dis[u],mp[u][i]));            if(k == dis[i]) continue;            if(!vis[i])            {                q.push(i);                vis[i] = 1;            }        }    }}int main(){    int t,u,v,w,i,j;    scanf("%d",&t);    for(j = 1; j <= t; ++j)    {        printf("Case %d:\n",j);        scanf("%d %d",&n,&m);        tp = 0;        memset(mp,-1,sizeof(mp));        for(i = 0; i < m; ++i)        {            scanf("%d %d %d",&u,&v,&w);            mp[u][v] = mp[v][u] = (mp[u][v] == -1)? w: min(w,mp[u][v]);        }        scanf("%d",&s);        SPFA();        for(i = 0; i < n; ++i)        {            if(dis[i] == -1) puts("Impossible");            else printf("%d\n",dis[i]);        }    }    return 0;}

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