spfa.zip_SPFA 无向图

// spfa算法.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include <cstdio> //using namespace std; struct node {int x; int value; int next; }; node e[60000]; int visited[1505],dis[1505],st[1505],queue[1000]; main() { int n,m,u,v,w,start,h,r,cur; freopen("c.in","r",stdin); freopen("c.out","w",stdout); while(scanf("%d%d",&n,&m)!=EOF) { for(int i=1;i<=1500;i++) {visited[i]=0; dis[i]=-1; st[i]=-1; } for( i=1;i<=m;i++) { scanf("%d%d%d\n",&u,&v,&w); e[i].x=v; e[i].value=w; e[i].next=st[u]; st[u]=i; } start=1; visited[start]=1; dis[start]=0; h=0; r=1; queue[r]=start; while(h!=r) { h=(h+1)%1000; cur=queue[h]; int tmp=st[cur]; visited[cur]=0; while(tmp!=-1) { if (dis[e[tmp].x]<dis[cur]+e[tmp].value) { dis[e[tmp].x]=dis[cur]+e[tmp].value; if(visited[e[tmp].x]==0) { visited[e[tmp].x]=1; r=(r+1)%1000; queue[r]=e[tmp].x; } } tmp=e[tmp].next; } } printf("%d\n",dis[n]); } return 0; }