hdu2767 proving equivalences, strong link to graph, Kosaraju algorithm

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The Kosaraju algorithm for strong linking to graph

Answer = Max (A, b) for the number of points after the indentation and the degree of 0 respectively;

scc_cnt = 1; Answer = 0

#include <cstdio> #include <algorithm> #include <vector> #include <cstring> #include <stack  >using namespace Std;const int maxn = 20000 + 10;vector<int> G[MAXN], g2[maxn];vector<int> S;int VIS[MAXN],    SCCNO[MAXN], scc_cnt;void dfs1 (int u) {if (Vis[u]) return;    Vis[u] = 1;    for (int i=0; i<g[u].size (); ++i) DFS1 (G[u][i]); S.push_back (u);}    void dfs2 (int u) {if (Sccno[u]) return;    Sccno[u] = scc_cnt; for (int i=0; i<g2[u].size (); ++i) DFS2 (G2[u][i]);}    void find_scc (int n) {scc_cnt = 0;    S.clear ();    memset (sccno, 0, sizeof sccno);    memset (Vis, 0, sizeof vis);    for (int i=0; i<n; ++i) DFS1 (i);            for (int i=n-1; i>=0;-I.) {if (!sccno[s[i])) {scc_cnt++;        DFS2 (S[i]);    }}}int IN[MAXN], Out[maxn];int main () {int T, n, M;    scanf ("%d", &t);        while (t--) {scanf ("%d%d", &n, &m); for (int i=0; i<n; ++i) {g[i].clear ();        G2[i].clear (); } For (int i=0; i<m; ++i) {int u, v; scanf ("%d%d", &u, &v); u--;            v--;            G[u].push_back (v);        G2[v].push_back (U);        } FIND_SCC (n);            if (scc_cnt==1) {printf ("0\n");        Continue        } memset (in, 0, sizeof in);        memset (out, 0, sizeof out);                for (int u=0, u<n; ++u) {for (int i=0; i<g[u].size (); ++i) {int &v = g[u][i];                    if (sccno[u]! = Sccno[v]) {out[sccno[u]]++;                in[sccno[v]]++;        }}} int a = 0, b = 0;            for (int i=1; i<=scc_cnt; ++i) {if (!in[i]) a++;        if (!out[i]) b++;    } printf ("%d\n", Max (A, b)); } return 0;}

hdu2767 proving equivalences, strong link to graph, Kosaraju algorithm