ZOJ 2770 Burn the Linked Camp(spfa&&bellman)

//差分约束  >=求最长路径 <=求最短路径   结果都一样
//spfa
#include<stdio.h>

#include<string.h>

#include<limits.h>

#include<queue>

using namespace std;

#define N 1010

#define M 1010*1010//注意边和点集的数组大小

struct edge

{

    int to,value,next;

};

struct edge edges[M];

int heads[N],len=0;

int dis[N];

int addedge(int u,int v,int w)

{

    edges[len].to=v,edges[len].value=w,edges[len].next=heads[u];

    heads[u]=len++;

    return 0;

}

int n,m;



int spfa(int v)

{

    queue<int> q;

    int inqueue[N];

    memset(inqueue,0,sizeof(inqueue)),inqueue[v]=1;

    q.push(v);

    for(int i=0;i<=n;i++) dis[i]=INT_MIN;

    dis[v]=0;

    int times[N];

    memset(times,0,sizeof(times)),times[v]=1;

    int temp=0;

    while(!q.empty()){

        int x=q.front();

        q.pop();

        inqueue[x]=0;



        for(int i=heads[x];i!=-1;i=edges[i].next){

            int to=edges[i].to,value=edges[i].value;

            if(value+dis[x]>dis[to]){

                dis[to]=value+dis[x];

                

                if(!inqueue[to]){  //注意已经在队列里面的不用再加入队列

                    inqueue[to]=1,q.push(to);

                    times[to]++;

                    if(times[x]>n){

                        return -1;//返回值有可能是0 不能将0作为区别的标记

                        

                    }

                    

                }

            }

        }

    }

    return dis[n];

}

int main(void)

{

    

    int i,num;

    while(scanf("%d%d",&n,&m)!=EOF){

        len=0;

        memset(heads,-1,sizeof(heads));

        for(i=1;i<=n;i++){

            scanf("%d",&num);

            addedge(i,i-1,-num);  

            addedge(0,i,0);  

        }

        for(i=1;i<=m;i++){

            int u,v,w;

            scanf("%d%d%d",&u,&v,&w);

            addedge(u-1,v,w);

        }

        

        int h=spfa(0);

        if(h!=-1) printf("%d\n",h);

        else printf("Bad Estimations\n");





    }

    return 0;

}
//bellman

#include <iostream>

#include <stdio.h>

#include <string.h>



using namespace std;

#define INF 2000000000

int u[12005],v[12005],w[12005],n,m,total,d[1005];

void Edge(int s,int e,int val){

	u[total]=s;

	v[total]=e;

	w[total++]=val;

}

int Bellman(){

	int i,e;

	for(i=1;i<=n;i++) d[i]=-INF;

	d[0]=0;

	for(i=1;i<=n;i++){

		for(e=0;e<total;e++){

			if(d[v[e]]<d[u[e]]+w[e])	

				d[v[e]]=d[u[e]]+w[e];

		}

	}

	int ans=d[n];

	for(e=0;e<total;e++)

		if(d[v[e]]<d[u[e]]+w[e]) ans=-1;

	return ans;

}

int main(){

	int a,b,c,cnt,i;

	while(scanf("%d%d",&n,&m)!=EOF){

		total=0;

		for(i=1;i<=n;i++){

			scanf("%d",&c);

			Edge(0,i,0);

			Edge(i,i-1,-c);

		}

		for(i=0;i<m;i++){

			scanf("%d%d%d",&a,&b,&c);

			Edge(a-1,b,c);

		}

		

		cnt=Bellman();

		for(i=0;i<n;i++) printf("%d ",d[i]);

		puts("");

		if(cnt==-1) cout<<"Bad Estimations\n";

		else cout<<cnt<<"\n";

	}

	return 0;

}