spfa模板

来源：互联网发布：c语言用什么编译器好编辑：程序博客网时间：2024/05/17 04:50
#include <stdio.h>#include <string.h>#include <stdlib.h>#include <iostream>#include <algorithm>#include <queue>using namespace std;const int inf =0x7ffffff;const int maxn=300001;//点数struct edge{    int from,to,w,next;}e[1000001];//边数int head[maxn];int vis[maxn];int dist[maxn];int n,m,t;//n个点，m条边，t用来生成边的标号void init()//建图前运行init{t=0;    memset(head,-1,sizeof(head));}void add(int i,int j,int w){    e[t].from=i;    e[t].to=j;    e[t].w=w;    e[t].next=head[i];    head[i]=t++;}void spfa(int s){    queue <int> q;    for(int i=1;i<=n;i++)    dist[i]=inf;    memset(vis,false,sizeof(vis));    q.push(s);    dist[s]=0;    while(!q.empty())    {        int u=q.front();        q.pop();        vis[u]=false;        for(int i=head[u];i!=-1;i=e[i].next)        {            int v=e[i].to;            if(dist[v]>dist[u]+e[i].w)            {                dist[v]=dist[u]+e[i].w;                if(!vis[v])                {                    vis[v]=true;                    q.push(v);                }            }        }    }}int main(){    int a,b,c,s,e;    scanf("%d%d",&n,&m);init();    while(m--)    {        scanf("%d%d%d",&a,&b,&c);        add(a,b,c);    }    scanf("%d%d",&s,&e);    spfa(s);    if(dist[e]==inf) printf("-1\n");    else printf("%d\n",dist[e]);    return 0;}
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