POJ 3169 Layout 差分约束系统

d_x <= d_(x+1)  --> d_x <= d_(x+1) + 0 

d_y - d_x <= maxd --> d_y <= d_x +maxd

d_y - d_x >= mind --> d_x <= d_y - mind 

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const int maxn=4100;
const int maxm=180000;
int n;
struct EdgeNode{
    int to;
    int w;
    int next;
};
struct BellmanFord{
    EdgeNode edges[maxm];
    int head[maxn],edge,n;
    bool vis[maxn];
    int outque[maxn];
    queue<int>que;
    int dis[maxn];
    void addedge(int u,int v,int c){
        edges[edge].w=c,edges[edge].to=v,edges[edge].next=head[u],head[u]=edge++;
    }
    void init(int n){
        memset(head,-1,sizeof(head));
        edge=0;
        this->n=n;
    }
    bool spfa(int s){
        int u;
        for (int i=0;i<=n;i++) dis[i]=INF;
        memset(vis,0,sizeof(vis));
        memset(outque,0,sizeof(outque));
        while (!que.empty()) que.pop();
        que.push(s);
        vis[s]=true;
        dis[s]=0;
        while (!que.empty()){
            u=que.front();
            que.pop();
            vis[u]=false;
            outque[u]++;
            if (outque[u]>n) return false;
            for (int i=head[u];i!=-1;i=edges[i].next){
                int v=edges[i].to;
                int w=edges[i].w;
                if (dis[v]==INF||dis[v]>dis[u]+w){
                    dis[v]=dis[u]+w;
                    if (!vis[v]){
                        vis[v]=true;
                        que.push(v);
                    }
                }
            }
        }
        return true;
    }
}g;
int ml,md;
int main(){
    while (~scanf("%d%d%d",&n,&ml,&md)){
        g.init(n);
        for (int i=1;i<n;i++){
            g.addedge(i+1,i,0);
        }
        for (int i=0;i<ml;i++){
            int x,y,z;
            scanf("%d%d%d",&x,&y,&z);
            g.addedge(x,y,z);
        }
        for (int i=0;i<md;i++){
            int x,y,z;
            scanf("%d%d%d",&x,&y,&z);
            g.addedge(y,x,-z);
        }
        if (g.spfa(1)){
            if (g.dis[n]==INF) printf("-2
");
            else printf("%d
",g.dis[n]);
        }
        else{
            printf("-1
");
        }
    }
	return 0;
}

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