Tarjan 联通图 Kuangbin 带你飞 联通图题目及部分联通图题目

Tarjan算法就不说了

想学看这

https://www.byvoid.com/blog/scc-tarjan/

https://www.byvoid.com/blog/biconnect/

下面是几份基本的模版

首先是无向图割点桥的代码

下面的代码是用于求割点数目的

其中add_block[u] = x  表示删除u点之后增加的联通块个数。注意是增加的联通块个数

const int MAXN = 1010;
const int MAXM = 10010;
const int INF = 0x3f3f3f3f;
struct Edge
{
    int u,v,next;
    int w;
    bool cut;
}edge[MAXN];
int head[MAXN],tot;
int Low[MAXN],DFN[MAXN],Stack[MAXN];
int Index,top;
bool Instack[MAXN];
bool cut[MAXN];
int add_block[MAXN];
int N,bridge;

void init()
{
    tot = 0;
    memset(head,-1,sizeof(head));
}

void add_edge(int u,int v,int w)
{
    edge[tot].u = u;
    edge[tot].v = v;
    edge[tot].w = w;
    edge[tot].next = head[u];
    head[u] = tot++;
}

void Tarjan(int u,int pre)
{
    int v;
    Low[u] = DFN[u] = ++Index;
    Stack[top++] = u;
    Instack[u] = true;
    int son = 0;
    for (int i = head[u] ; i != -1 ; i = edge[i].next)
    {
        v = edge[i].v;
        if (v == pre) continue;
        if (!DFN[v])
        {
            son++;
            Tarjan(v,u);
            if (Low[u] > Low[v]) Low[u] = Low[v];
            if (Low[u] > DFN[v])
            {
                bridge++;
                edge[i].cut = true;
                edge[i ^ 1].cut = true;
            }
            if (u != pre && Low[v] >= DFN[u])
            {
                cut[u] = true;
                add_block[u]++;
            }
        }
        else if (Low[u] > DFN[v])
            Low[u] = DFN[v];
    }
    if (u == pre && son > 1) cut[u] = true;
    if (u == pre) add_block[u] = son - 1;
    Instack[u] = false;
    top--;
}

void slove()
{
    memset(DFN,0,sizeof(DFN));
    memset(Instack,false,sizeof(Instack));
    memset(cut,false,sizeof(cut));
    memset(add_block,0,sizeof(add_block));
    top = Index = 0;
    bridge = 0;
    for (int i = 1 ; i <= N ; i++)
        if (!DFN[i]) Tarjan(i,i);
    int ret = 0;
    for (int i = 1 ; i <= N ; i++)
        if (cut[i]) ret++;
    printf("%d\n",ret);
}

View Code