RE4个点求助

#include <bits/stdc++.h>
using namespace std;
#define reg register
#define ll long long
static char in[50000000],out[20],ch[20],*p=in,*q=out,*t=ch;
inline int read(){
    reg int x=0;
    while(*p<48)++p;
    while(*p>47)x=(x+(x<<2)<<1)+(*p++^48);
    return x;
}
inline void write(reg ll x){
    if(!x)putchar('0');
    else {
        while(x)*t++=x%10+48,x/=10;
        while(t!=ch)*q++=*--t;
    }
}
static int n,m,dis[1000001],head[1000001],head1[1000001],N;
struct Node{
    int u,v,w,nxt;
}edges[1000001],edges1[1000001];
struct node{
    int dis,to;
};
struct cmp{
    inline bool operator()(node a,node b){
        return a.dis>b.dis;
    }
};
priority_queue<node,vector<node>,cmp > Q;
inline void addedge(int u,int v,int w){
    edges[++N]=Node{u,v,w,head[u]},head[u]=N;
}
inline void addedge1(int u,int v,int w){
    edges1[N]=Node{u,v,w,head1[u]},head1[u]=N;
}
int main(){
    freopen("1.in","r",stdin);
    fread(in,1,10000000,stdin);
    n=read(),m=read();
    while(m--){
        int u=read(),v=read(),w=read();
        u!=v&&(addedge(u,v,w),addedge1(v,u,w),0);
    }
    int *S=dis,*E=dis+n;
    while(S!=E)*++S=2000000000;
    dis[1]=0,Q.push(node{0,1});
    while(!Q.empty()){
        node now=Q.top();Q.pop();
        if(now.dis==dis[now.to]){
            reg int v,w,tp=now.to;
            for(reg int i=head[now.to];i;i=edges[i].nxt)
                v=edges[i].v,w=edges[i].w,
                dis[v]>dis[tp]+w&&(dis[v]=dis[tp]+w,Q.push(node{dis[v],v}),0);
        }
    }reg long long ans=0;
    S=dis+1,E=dis+n;
    while(S!=E)ans+=*++S;
    S=dis+1,E=dis+n;
    while(S!=E)*++S=2000000000;
    Q.push(node{0,1});
    while(!Q.empty()){
        node now=Q.top();Q.pop();
        if(now.dis==dis[now.to]){
            reg int v,w,tp=now.to;
            for(reg int i=head1[now.to];i;i=edges1[i].nxt)
                v=edges1[i].v,w=edges1[i].w,
                dis[v]>dis[tp]+w&&(dis[v]=dis[tp]+w,Q.push(node{dis[v],v}),0);
        }
    }
    S=dis+1,E=dis+n;
    while(S!=E)ans+=*++S;
    write(ans);
    fwrite(out,1,q-out,stdout);
    return 0;
}