[dij] Codeforces Round #675 (Div. 2) D. Returning Home

注意搜到终点就不要搜了，不然会TLE

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i,a,b) for(ll i=a;i<=b;i++)
#define per(i,a,b) for(ll i=a;i>=b;i--)
#define go(i,a) for(ll i=head[a];i;i=e[i].to)
#define endl '
'
#define mem(x) memset(x,0,sizeof(x))
const ll amn=1e6+5,inf=1e18;
char a[amn];
ll n,m,k;

ll head[amn],etot=0;
struct eg{
    ll to,u,v,w;
    eg(){}
    eg(ll to,ll u,ll v,ll w):to(to),u(u),v(v),w(w){}
}e[amn<<1];
void add(ll u,ll v,ll w){
    e[++etot]=eg(head[u],u,v,w);
    head[u]=etot;
    e[++etot]=eg(head[v],v,u,w);
    head[v]=etot;
}

struct nd{
    ll x,y,i;
    nd(){}
    nd(ll x,ll y,ll i):x(x),y(y),i(i){}
}np[amn];

bool cmp1(nd a,nd b){return a.x<b.x;}
bool cmp2(nd a,nd b){return a.y<b.y;}
ll gd(ll a,ll b){return abs(a-b);}
ll ans=0;

struct node{
    ll i,d;
    node(){}
    node(ll i,ll d):i(i),d(d){}
    friend bool operator < (node a,node b){
        return a.d>b.d;
    }
};
ll vis[amn];
ll dis[amn];
void dij(ll st){
    rep(i,0,m+1){
        vis[i]=0;
        dis[i]=inf;
    }
    dis[st]=0;

    priority_queue<node> q;
    while(q.size())q.pop();
    q.push(node(st,0));

    while(q.size()){
        node x=q.top();q.pop();
        ll u=x.i,d=x.d;
        if(vis[u])continue;

        if(u==m+1)break;    ///因为是优先队列，所以搜到终点就不用搜了，如果继续搜就会在TEST4那TLE

        vis[u]=1;
        go(i,u){
            ll v=e[i].v,w=e[i].w;
            if(!vis[v]&&d+w<dis[v]){
                dis[v]=d+w;
                q.push(node(v,dis[v]));
            }
        }
    }
}

int main(){
//    ios::sync_with_stdio(0);
    ll T=1;
//    cin>>T;
    while(T--){
        scanf("%lld%lld",&n,&m);
        ll sx,sy,fx,fy;
        scanf("%lld%lld%lld%lld",&sx,&sy,&fx,&fy);
        rep(i,1,m){
            scanf("%lld%lld",&np[i].x,&np[i].y);
            np[i].i=i;
        }

        add(0,m+1,gd(sx,fx)+gd(sy,fy));
        rep(i,1,m){
            add(0,i,min(gd(sx,np[i].x),gd(sy,np[i].y)));
            add(i,m+1,gd(fx,np[i].x)+gd(fy,np[i].y));
        }

        sort(np+1,np+1+m,cmp1);
        rep(i,2,m){
            add(np[i-1].i,np[i].i,gd(np[i-1].x,np[i].x));
        }
        sort(np+1,np+1+m,cmp2);
        rep(i,2,m){
            add(np[i-1].i,np[i].i,gd(np[i-1].y,np[i].y));
        }

//        rep(i,1,etot){
//            cout<<e[i].to<<' '<<e[i].u<<' '<<e[i].v<<' '<<e[i].w<<endl;
//        }

        ans=1e18;
        dij(0);
//        rep(i,0,m+1)cout<<i<<' '<<dis[i]<<endl;
        printf("%lld
",dis[m+1]);
    }
}