Poj 1523 SPF (tarjan cut point)

The question is to give a connected undirected graph, find all the cut points of the graph, and output the cut points and the edge to be removed, it will become the basic question of several connected component ideas to use tarjan to find the cut point, we need to understand the principle of the tarjan algorithm. Code

/** =================================================== =================== * This is a solution for ACM/ICPC problem ** @ source: poj-1523 SPF * @ description: Graph connectivity-tarjan cut point * @ author: shuangde * @ blog: blog.csdn.net/shuangde800 * @ email: zengshuangde@gmail.com * Copyright (C) 2013/09/04 All rights reserved. * ===================================================== ===================*/# include <iostream> # include <cstdio> # inc Lude <algorithm> # include <vector> # include <cmath> # include <cstring> using namespace std; typedef long int64; const int INF = 0x3f3f3f; const int MAXN = 1010; int n; bool OK; int cnt [MAXN]; namespace Adj {int size, head [MAXN]; struct Node {int v, next;} E [MAXN * 2]; inline void initAdj () {size = 0; memset (head,-1, sizeof (head);} inline void addEdge (int u, int v) {E [size]. v = v; E [size]. next = Head [u]; head [u] = size ++ ;}} using namespace Adj; namespace Tarjan {bool vis [MAXN]; int dfn [MAXN], low [MAXN], idx; inline void initTarjan () {idx = 1; memset (vis, 0, sizeof (vis); memset (dfn, 0, sizeof (dfn); memset (low, 0, sizeof (low);} void tarjan (int u) {vis [u] = true; dfn [u] = low [u] = idx ++; for (int e = head [u]; e! =-1; e = E [e]. next) {int v = E [e]. v; if (vis [v]) {low [u] = min (low [u], dfn [v]);} else {tarjan (v ); low [u] = min (low [u], low [v]); if (u = 1) {++ cnt [u]; if (cnt [u] = 2) OK = true;} else if (low [v]> = dfn [u]) {OK = true; ++ cnt [u] ;}}}} using namespace Tarjan; int main () {int cas = 1; int u, v; while (~ Scanf ("% d", & u) {scanf ("% d", & v); initAdj (); n = 0; n = max (n, max (u, v); addEdge (u, v); addEdge (v, u); while (~ Scanf ("% d", & u) {scanf ("% d", & v); n = max (n, max (u, v )); addEdge (u, v); addEdge (v, u) ;}if (cas! = 1) puts (""); printf ("Network # % d \ n", cas ++); memset (cnt, 0, sizeof (cnt )); OK = false; initTarjan (); tarjan (1); if (! OK) puts ("No SPF nodes"); else {if (cnt [1]> 1) printf ("SPF node % d leaves % d subnets \ n", 1, cnt [1]); for (int I = 2; I <= n; ++ I) {if (cnt [I]) printf ("SPF node % d leaves % d subnets \ n", I, cnt [I] + 1) ;}} return 0 ;}