diff --git a/POJ/1236/1236.cpp b/POJ/1236/1236.cpp new file mode 100644 index 00000000..02cc5c82 --- /dev/null +++ b/POJ/1236/1236.cpp @@ -0,0 +1,75 @@ +#include +#include +#include + +using std::cin; +using std::cout; +using std::endl; + +// Limits +const int N = 105; + +int n, x, ans1, ans2; +std::vector g[N]; +int din[N], dout[N]; // 图的入度、出度 + +// Tarjan +int cnt, dfn[N], low[N]; +int scc_cnt, id[N]; +std::stack st; +bool vis[N]; + +void tarjan(int u) { + dfn[u] = low[u] = ++cnt; + st.push(u); + vis[u] = true; + for (int i = 0; i < g[u].size(); i++) { + int v = g[u][i]; + if (!dfn[v]) { + tarjan(v); + low[u] = std::min(low[u], low[v]); + } else if (vis[v]) { + low[u] = std::min(low[u], dfn[v]); + } + } + if (dfn[u] == low[u]) { + scc_cnt++; + int v; + do { + v = st.top(); + st.pop(); + id[v] = scc_cnt; + vis[v] = false; + } while (v != u); + } +} + +int main() { + cin >> n; + for (int i = 1; i <= n; i++) { + while (cin >> x, x) { + g[i].push_back(x); + } + } + for (int i = 1; i <= n; i++) { + if (!dfn[i]) { + tarjan(i); + } + } + for (int i = 1; i <= n; i++) { + for (int j = 0; j < g[i].size(); j++) { + int v = g[i][j]; + if (id[i] != id[v]) { + dout[id[i]]++; + din[id[v]]++; + } + } + } + for (int i = 1; i <= scc_cnt; i++) { + if (!din[i]) ans1++; + if (!dout[i]) ans2++; + } + cout << ans1 << endl + << (scc_cnt == 1 ? 0 : std::max(ans1, ans2)) << endl; + return 0; +}