poj 3352 边连通分量

思路与poj3177一模一样。

#include<iostream>

#include<cstdio>

#include<cstring>

#include<algorithm>

#include<queue>

#define Maxn 1010

#define Maxm Maxn*Maxn

#define inf 0x7fffffff

using namespace std;

int dfn[Maxn],low[Maxn],degree[Maxn],e,n,lab,index[Maxn];

struct Edge{

    int to,from,next,v;

}edge[Maxm];

void init()

{

    memset(dfn,0,sizeof(dfn));

    memset(low,0,sizeof(low));

    memset(degree,0,sizeof(degree));

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

    e=lab=0;

}

void addedge(int from, int to)

{

    edge[e].v=0;

    edge[e].from=from;

    edge[e].to=to;

    edge[e].next=index[from];

    index[from]=e++;

    edge[e].v=0;

    edge[e].from=to;

    edge[e].to=from;

    edge[e].next=index[to];

    index[to]=e++;

}

void dfs(int u)

{

    dfn[u]=low[u]=++lab;

    int i,j,temp;

    for(i=index[u];i!=-1;i=edge[i].next)

    {

        temp=edge[i].to;

        if(edge[i].v) continue;

        edge[i].v=edge[i^1].v=1;

        if(!dfn[temp])

        {

            dfs(temp);

            low[u]=min(low[u],low[temp]);

        }

        low[u]=min(low[u],dfn[temp]);

    }

}

int solve()

{

    int i,j,temp=0;

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

    {

        for(j=index[i];j!=-1;j=edge[j].next)

        {

            if(low[i]!=low[edge[j].to])

                degree[low[i]]++;

        }

    }

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

        if(degree[i]==1)

            temp++;

    return (temp+1)/2;

}

int main()

{

    int m,i,j,a,b;

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

    {

        init();

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

        {

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

            addedge(a,b);

        }            

        dfs(1);

        printf("%d\n",solve());

        

    }

    return 0;

}