SPFA+邻接表

#include <stdio.h>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <queue>
using namespace std;
const int maxn=300001;
const int inf =0x7ffffff;
struct edge
{
    int from,to,w,next;
}e[1000001];
int head[maxn];
int vis[maxn];
int path[maxn];
int dist[maxn];
int n,m,t;
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=0;i<n;i++)
    {
        dist[i]=inf;
        path[i]=s;
    }
    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;
                path[v]=u;
                if(!vis[v])
                {
                    vis[v]=true;
                    q.push(v);
                }
            }
        }
    }
}
int main()
{
    int a,b,c,s,e;
    int i,j;
    int shortest[maxn];
    scanf("%d",&n);
    t=0;
    memset(head,-1,sizeof(head));
    while(1)
    {
        scanf("%d%d%d",&a,&b,&c);
        if(a==-1&&b==-1&&c==-1) break;
        add(a,b,c);
    }
    spfa(0);
    for(i=1;i<n;i++)
    {
        printf("%d\t",dist[i]);
        memset(shortest,0,sizeof(shortest));
        int k=0;
        shortest[k]=i;
        while(path[shortest[k]]!=0)
        {
            k++;
            shortest[k]=path[shortest[k-1]];
        }
        k++;
        shortest[k]=0;
        for(j=k;j>0;j--)
        printf("%d->",shortest[j]);
        printf("%d\n",shortest[j]);
    }
    return 0;
}