Luogu p1144 shortest circuit count

Give a N vertices M Undirected graphs with edges , The vertex number is 1-N. Ask from the top 1 Start , There are several shortest paths to every other point .
Original link
spfa Combination with chained forward star , It's a template question

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
const ll INF=0x7fffffff;
const int N = 1e6+5;
const int mod=100003;
int n,m;
struct node{
    
    int x;
    int next;
}edge[N<<2];
int vis[N],ans[N],dis[N],head[N];
int cnt;
void add(int x,int y){
    
    edge[++cnt].x=y;
    edge[cnt].next=head[x];
    head[x]=cnt;
    edge[++cnt].x=x;
    edge[cnt].next=head[y];
    head[y]=cnt;
}
void SPFA(){
    
    for(int i=1;i<=n;i++){
    
        dis[i]=INF;
        vis[i]=0;
    }
    vis[1]=1;
    dis[1]=0;
    ans[1]=1;
    queue<int> q;
    q.push(1);
    while(!q.empty()){
    
        int u=q.front();
        q.pop();
        for(int i=head[u];i;i=edge[i].next){
    
            int x = edge[i].x;
            if(dis[x]>dis[u]+1){
    
                dis[x]=dis[u]+1;
                ans[x] = ans[u];
                if(!vis[x]){
    
                    vis[x]=1;
                    q.push(x);
                }
            }
            else if(dis[x]==dis[u]+1)
                ans[x]=(ans[x]+ans[u])%mod;
        }
    }
}
int main()
{
    
    ios::sync_with_stdio(false);
    int x,y;
    cin>>n>>m;
    for(int i=0;i<m;i++){
    
        cin>>x>>y;
        add(x,y);
    }
    SPFA();
    for(int i=1;i<=n;i++){
    
        cout<<ans[i]<<endl;
    }
    return 0;
}