【双连通】双连通模板 Tarjan

来源：互联网发布：北京关键词优化编辑：程序博客网时间：2024/04/28 18:51

比起求无向图关节点的算法，只是多了一个栈，用来储存不存在关节点的所有边，遇到关节点之后弹出所有边进行储存

#include <cstdio>#include <cstdlib>#include <cstring>#include <stack>#include <vector>#define Mem(f, x) memset(f, x, sizeof(f))#define PB push_backusing namespace std;const int N = 1e5, M = 1e5;struct Pair {    int u, v;    Pair(){}    Pair(int _u, int _v):        u(_u), v(_v){}};int dfn[N], iscut[N], bcc_id[N];stack <Pair> s;vector <int> bcc[N];int bcc_cnt, deep;int dfs(int u, int fa){    int lowu = dfn[u] = ++deep;    int son = 0;    for(int i = head[u]; ~i; i = e[i].next) {        int v = e[i].v;        Pair p = Pair(u, v);        if(!dfn[v]) {            s.push(p);            son++;            int lowv = dfs(v, u);            lowu = min(lowu, lowv);            if(lowv >= dfn[u]) {                iscut[u] = 1;                bcc_cnt++;//从1开始编号的                bcc[bcc_cnt].clear();                while(1) {                    Pair x = s.top(); s.pop();                    if(bcc_id[x.u] != bcc_cnt) {                        bcc[bcc_cnt].PB(x.u);                         bcc_id[x.u] = bcc_cnt;                    }                    if(bcc_id[x.v] != bcc_cnt) {                        bcc[bcc_cnt].PB(x.v);                        bcc_id[x.v] = bcc_cnt;                    }                    if(x.u == u && x.v == v) break;                }//弹出所有边进行储存，直到遇见了u->v            }        }        else if(dfn[v] < dfn[u] && v != fa) {            s.push(p);            lowu = min(lowu, dfn[v]);        }    }    if(fa == -1 && son == 1) iscut[u] = 0;    return lowu;}void tarjan(int n){    for(int i = 0; i < n; i++) {        dfn[i] = iscut[i] = bcc_id[i] = 0;    }    deep = bcc_cnt = 0;    for(int i = 0; i < n; i++) {//为防止图不连通        if(!dfn[i]) dfs(i, -1);    }}int main(){    return 0;}

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