HDU4109 Instrction Arrangement 拓扑排序 关键路径

标签：c++

5 2
1 2 1
3 4 1

2
Hint
In the 1st ns, instruction 0, 1 and 3 are executed;
In the 2nd ns, instruction 2 and 4 are executed.
So the answer should be 2.
 

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
#include<vector>
#include<algorithm>
using namespace std;
struct node
{
    int to,value;
};
vector<node>next[1005];      //向量+结构体 邻接表
int in_degree[1005];          //节点的入度
int finish[1005];            //节点的开始时间
int m,n;
void topsort()
{
    queue<int>q;
    int i,j;
    int now;
    for(i=0;i<m;i++)
        if(in_degree[i]==0)
            {
                finish[i]=1;       //题意
                q.push(i);
            }
    while(!q.empty())
    {
        now=q.front();
      //  cout<<now<<endl;
        q.pop();
        for(i=0;i<next[now].size();i++) 
        {
            int b=next[now][i].to;
            int v=next[now][i].value;
            finish[b]=max(finish[b],finish[now]+v);     //某个工程的开始时间
            in_degree[b]--;
            if(in_degree[b]==0)
                q.push(b);
        }
    }
    return;
}
int main()
{
    int i,j;
    while(~scanf("%d%d",&m,&n))
    {
        memset(finish,0,sizeof(finish));
        memset(in_degree,0,sizeof(in_degree));
        for(i=0; i<=m; i++)
            next[i].clear();
        int a,b,c;
        node d;
        while(n--)
        {
            scanf("%d%d%d",&a,&b,&c);
            d.to=b;
            d.value=c;
            next[a].push_back(d);
            in_degree[b]++;
        }
        topsort();
        int ans=0;
        for(i=0;i<=m;i++)
            if(finish[i]>ans)
                ans=finish[i];
            cout<<ans<<endl;
    }
    return 0;
}

HDU4109 Instrction Arrangement 拓扑排序 关键路径

标签：c++

原文地址：http://blog.csdn.net/axuan_k/article/details/41788033