链式前向星BFS

本文链接:http://i.cnblogs.com/EditPosts.aspx?postid=5399068

采用链式前向星的BFS:

#include <iostream>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <queue>
using namespace std;
typedef long long LL;
 
const int maxN =  + ;
const int maxM =  + ;
int head[maxN];
int visited[maxN];
int N, M;
 
struct EdgeNode
{
    int to;
    int w;
    int next;
};
EdgeNode Edges[maxM];
 
void BFS(int x)
{
    memset(visited, , sizeof(visited));
    queue<int> initQueue;
    for(int i = ; i <= N; i++)
    {
        if( !visited[i] )
        {
            visited[i] = ;
            initQueue.push( i );
            while( !initQueue.empty() )
            {
                i = initQueue.front(); //取得对头的节点，一定是下次待扩展的节点
                initQueue.pop();//队顶元素出队（出队代表着访问到了这个节点）
       　　　　　//遍历与当前节点相连的节点
                for(int j = head[i]; j !=  -; j = Edges[j].next)
                {
           　　　　　　 //如果没被访问，入队
                    if( !visited[ Edges[j].to ])
                    {
                        visited[ Edges[j].to ] = ;
                        initQueue.push( Edges[j].to );
                    }
                }
            }
        }
    }
}
 
int main()
{
    freopen("input.txt", "r", stdin);
    memset(head, -, sizeof(head));
    cin >> N >> M;
    for(int i = ; i <= M; i++)
    {
        int x, y ,z;
        cin >> x >> y >> z;
        Edges[i].to = y;
        Edges[i].w = z;
        Edges[i].next = head[x];
        head[x] = i;
    }
    memset(visited, , sizeof(visited));
    BFS();
    return ;
}