zoj 2770 Burn the Linked Camp 差分约束

/*
author:jxy
lang:C/C++
university:China,Xidian University
**If you need to reprint,please indicate the source**
*/
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <queue>
#define INF 1E9
using namespace std;
int Dis[1005];
int U[100005];
int next[100005];
int W[100005];
int cnt;
int first[1005];
int n,m;
int add(int v,int u,int w)
{
next[cnt]=first[v];
first[v]=cnt;
U[cnt]=u;
W[cnt]=w;
cnt++;
}
bool inq[1005];
int dq[1005];
bool spfa(int v)
{
memset(Dis,63,sizeof(Dis));
memset(inq,0,sizeof(inq));
memset(dq,0,sizeof(dq));
queue<int> q;
q.push(v);
Dis[v]=0;
int i,u,now,t;
while(!q.empty())
{
v=q.front();q.pop();
inq[v]=0;dq[v]++;
if(dq[v]>=n)return 1;
for(i=first[v];i!=-1;i=next[i])
{
u=U[i];
t=Dis[v]+W[i];
if(t>=Dis[u])continue;
Dis[u]=t;
if(inq[u])continue;
inq[u]=1;
q.push(u);
}
}
return 0;
}
int main()
{
while(~scanf("%d%d",&n,&m))
{
cnt=0;
memset(first,-1,sizeof(first));
int i,v,u,s;
for(i=1;i<=n;i++)
{
scanf("%d",&s);
add(i-1,i,s);
add(i,i-1,0);
}
for(i=0;i<m;i++)
{
scanf("%d%d%d",&u,&v,&s);
add(v,u-1,-s);
}
if(spfa(n))printf("Bad Estimations\n");
else printf("%d\n",-Dis[0]);
}
}