poj 3249 Test for Job dp(动态规…

题目意思是求最短路，但是因为此图没有环，所以可以用动态规划的办法按照拓扑序列递推求解

第一次调用系统的链表

自己写的链表居然T了...

#include <iostream>
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<vector>
using namespace std;
const int maxn=100001;
const int inf=1<<30;
int gain[maxn],dist[maxn];
int stack[maxn],top;
int in[maxn],out[maxn];
int n,m;
vector<int> graph[maxn];

struct node
{
    int to;
    struct node *next;
}e[maxn];

int edgeini(int n)
{
    for(int i=1;i<=n;i++) graph[i].clear();
}

 

int topo()
{
    for(int i=1;i<=n;i++) dist[i]=-inf;
    int top=0;

    for(int i=1;i<=n;i++)
    if(!in[i])
    {
        dist[i]=gain[i];
        stack[++top]=i;
    }
    int k=0;
    while(top<n)
    {
        int t=stack[++k];
        for(int j=0;j<graph[t].size();j++)
        {
            int v=graph[t][j];
            in[v]--;
            if(!in[v])
            {
                stack[++top]=v;
            }
            if(dist[v]<dist[t]+gain[v])
            dist[v]=dist[t]+gain[v];
        }
    }
}

int main()
{
//    freopen("in.txt","r",stdin);
    while(scanf("%d %d",&n,&m)!=EOF)
    {
        edgeini(n);
        memset(in,0,sizeof(in));
        memset(out,0,sizeof(out));
        for(int i=1;i<=n;i++) scanf("%d",&gain[i]);

        for(int i=1;i<=m;i++)
        {
            int from,to;
            scanf("%d %d",&from,&to);
            in[to]++;
            out[from]++;
            graph[from].push_back(to);
        }
        topo();
        int ans=-inf;
        for(int i=1;i<=n;i++)
        if(!out[i]&&dist[i]>ans)
        ans=dist[i];
        printf("%d\n",ans);
    }
    return 0;
}