ZOJ2770 差分約束

#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;

#define EDGE_COUNT 30000
#define PNT_COUNT 2000
#define INF 0x1f1f1f1f

struct edge
{
	int adj;
	int point;
	int weight;
	edge(int a,int p,int w):adj(a),point(p),weight(w){}
	edge():adj(0),point(0),weight(0){}
};

edge e[EDGE_COUNT];
int dis[PNT_COUNT];

int c[1005];

bool bellman_ford(int src,int edge_count,int pnt_count)
{
	memset(dis,0x1f,sizeof(dis));
	dis[src]=0;
	for(int i=1;i<pnt_count;i++)
	{
		for(int j=1;j<=edge_count;j++)
		{
			if(dis[e[j].adj]<INF&&dis[e[j].adj]+e[j].weight<dis[e[j].point])
			{
				dis[e[j].point]=dis[e[j].adj]+e[j].weight;
			}
		}
	}
	for(int i=1;i<=edge_count;i++)
	{
		if(dis[e[i].adj]<INF&&dis[e[i].adj]+e[i].weight<dis[e[i].point])
		{
			return 0;
		}
	}
	return 1;
}

int main()
{
	int n,m;
	while(~scanf("%d%d",&n,&m))
	{
		for(int i=1;i<=n;i++)
		{
			scanf("%d",&c[i]);
		}
		for(int i=1;i<=m;i++)
		{
			int u,v,w;
			scanf("%d%d%d",&u,&v,&w);
			e[i]=edge(v,u-1,-w);
		}
		for(int i=1;i<=n;i++)
		{
			e[m+i]=edge(i-1,i,c[i]);
			e[m+n+i]=edge(i,i-1,0);
		}
		if(bellman_ford(n,m+n+n,n+1))printf("%d\n",-dis[0]);
		else printf("Bad Estimations\n");
	}
	return 0;
}