poj 3255 Roadblocks

求次短路。水过

#include<iostream>#include<queue>using namespace std;#define N 5005#define inf 100000000struct node{int dist,v;bool flag;};struct cmp{bool operator()(node a,node b){return a.dist>b.dist;}};priority_queue<node,vector<node>,cmp>que;struct edge{int v,d;edge *next;};edge *g[N];int dist[N][2];bool use[N][2];void add_edge(int u,int v,int d){edge *ptr=new edge;ptr->v=v;ptr->d=d;ptr->next=g[u];g[u]=ptr;return ;}void dijkstra(int s,int n){node temp;int d,v,flag,u,w,i;for(i=1;i<=n;i++)dist[i][0]=dist[i][1]=inf;dist[s][0]=0;memset(use,0,sizeof(use));temp.dist=temp.flag=0,temp.v=s;while(!que.empty())que.pop();que.push(temp);while(!que.empty()){temp=que.top();que.pop();v=temp.v,d=temp.dist,flag=temp.flag;if(use[v][flag])continue;use[v][flag]=1;for(edge *ptr=g[v];ptr;ptr=ptr->next){u=ptr->v,w=ptr->d;if(d+w<dist[u][0]){dist[u][1]=dist[u][0];dist[u][0]=d+w;temp.v=u,temp.flag=0,temp.dist=dist[u][0];que.push(temp);temp.flag=1,temp.dist=dist[u][1];que.push(temp);}else if(d+w<dist[u][1]){dist[u][1]=d+w;temp.dist=dist[u][1];temp.flag=1;temp.v=u;que.push(temp);}}}}int main(){int n,m,i,a,b,d;scanf("%d%d",&n,&m);for(i=1;i<=n;i++)g[i]=NULL;for(i=1;i<=m;i++){scanf("%d%d%d",&a,&b,&d);add_edge(a,b,d);add_edge(b,a,d);}dijkstra(1,n);printf("%d/n",dist[n][1]);return 0;}