P5960 【模板】差分约束——做法1

//https://www.luogu.com.cn/problem/P5960
#include <bits/stdc++.h>
using namespace std;
const int N=5e3+10,M=2*N;
int head[N],Next[M],to[M],weight[M],cnt;
int dist[N],update[N];
int q[N];
bool enter[N];
int h,t;
int n,m;
void prepare(){
	h=t=0;
	cnt=1;
	memset(head,0,sizeof head);
	memset(dist,0x3f,sizeof dist);
	memset(update,0,sizeof update);
	memset(enter,false,sizeof enter);
}
void addEdge(int u,int v,int w){
	Next[cnt]=head[u];
	to[cnt]=v;
	weight[cnt]=w;
	head[u]=cnt++;
}
bool spfa(int s){
	dist[s]=0;
	update[s]=1;
	q[t]=s;
	t=(t+1)%N;
	enter[s]=true;
	while(h!=t){
		int u=q[h];
		h=(h+1)%N;
		enter[u]=false;
		for(int ei=head[u];ei;ei=Next[ei]){
			int v=to[ei],w=weight[ei];
			if(dist[v]>dist[u]+w){
				dist[v]=dist[u]+w;
				if(!enter[v]){
					if(++update[v]>n) return true;
					q[t]=v;
					t=(t+1)%N;
					enter[v]=true;
				}
			}
		}
	}
	return false;
}
int main(){
	scanf("%d%d",&n,&m);
	prepare();
	for(int i=1;i<=n;i++) addEdge(0,i,0);
	for(int i=1,u,v,w;i<=m;i++){
		scanf("%d%d%d",&u,&v,&w);
		addEdge(v,u,w);
	}
	if(spfa(0)) puts("NO");
	else{
		for(int i=1;i<=n;i++) printf("%d ",dist[i]);
	}
	return 0;
}