Tram POJ - 1847 spfa

#include<iostream>
#include<algorithm>
#include<queue>
#include<cstdio>
#include<cstring>
using namespace std;
const int N=1100,INF=0x3f3f3f3f;
int h[N],e[N],v[N],w[N],ne[N],idx;
int dist[N];
bool st[N];
int n,beg,en,ans; 
void add(int a,int b,int c)
{
    v[idx]=a;
    e[idx]=b;
    w[idx]=c;
    ne[idx]=h[a];
    h[a]=idx++;
}
void spfa(int sx)
{
    queue<int>q;
    memset(dist,0x3f,sizeof dist);
    memset(st,0,sizeof st);
    st[sx]=1;
    q.push(sx);
    dist[sx]=0;
    while(q.size())
    {
        int u=q.front();
        q.pop();
        st[u]=0;
        for(int i=h[u];i!=-1;i=ne[i])
        {
            int j=e[i];
            if(dist[j]>dist[u]+w[i])
            {
                dist[j]=dist[u]+w[i];
                if(!st[j])
                {
                    st[j]=1;
                    q.push(j);
                }
            }
        }
    }
    if(dist[en]==INF)
        cout<<"-1"<<endl;
    else
        cout<<dist[en]<<endl;
}
void init()
{
    ans=0;
    memset(h,-1,sizeof(h));
}
void getmap()
{
    int i,j;
    for(i=1;i<=n;i++)
    {
        int k;
        scanf("%d",&k);
        for(j=0;j<k;j++)
        {
            int a;
            scanf("%d",&a);
            if(j==0)
            add(i,a,0);
            else
            add(i,a,1);
        }
    }
}
int main()
{
    while(~scanf("%d%d%d",&n,&beg,&en))
    {
        init();
        getmap();
        spfa(beg);
    }
    return 0;
}

标签：sx,dist,idx,Tram,1847,st,int,spfa,include
来源： https://www.cnblogs.com/QingyuYYYYY/p/12236327.html