From 047282d215e1d20ecc71259eda722719525c1123 Mon Sep 17 00:00:00 2001
From: Bruno Freitas Tissei <bft15@inf.ufpr.br>
Date: Mon, 12 Feb 2018 00:34:21 -0200
Subject: [PATCH] Add kosaraju
Signed-off-by: Bruno Freitas Tissei <bft15@inf.ufpr.br>
---
graph/articulations_bridges.cpp | 5 +++
graph/kosaraju.cpp | 62 +++++++++++++++++++++++++++++++++
2 files changed, 67 insertions(+)
create mode 100644 graph/kosaraju.cpp
diff --git a/graph/articulations_bridges.cpp b/graph/articulations_bridges.cpp
index a88d707..e2dc350 100644
--- a/graph/articulations_bridges.cpp
+++ b/graph/articulations_bridges.cpp
@@ -36,3 +36,8 @@ void dfs(int x) {
}
}
}
+
+void tarjan(int v) {
+ memset(parent, -1, sizeof parent);
+ dfs(v);
+}
diff --git a/graph/kosaraju.cpp b/graph/kosaraju.cpp
new file mode 100644
index 0000000..6808abd
--- /dev/null
+++ b/graph/kosaraju.cpp
@@ -0,0 +1,62 @@
+/**
+ * Kosaraju
+ *
+ * Complexity (Time): O(n + m)
+ * Complexity (Space): O(n + m)
+ */
+
+stack<int> S;
+vector<int> graph[MAX];
+vector<int> transp[MAX];
+
+bool cont[MAX];
+
+// Traverse a SCC
+void dfs(int x) {
+ // x belong to current scc
+ cont[x] = true;
+
+ for (auto i : transp[x])
+ if (!cont[i])
+ dfs(i);
+}
+
+// Fill stack with DFS starting points to find SCC
+void fill_stack(int x) {
+ cont[x] = true;
+
+ for (auto i : graph[x])
+ if (!cont[i])
+ fill_stack(i);
+
+ S.push(x);
+}
+
+// Return number of SCC of a graph with n vertices
+int kosaraju(int n) {
+ int scc = 0;
+
+ memset(cont, 0, sizeof cont);
+ for (int i = 0; i < n; ++i)
+ if (!cont[i])
+ fill_stack(i);
+
+ // Transpose graph
+ for (int i = 0; i < n; ++i)
+ for (auto j : graph[i])
+ transp[j].push_back(i);
+
+ // Count SCC
+ memset(cont, 0, sizeof cont);
+ while (!S.empty()) {
+ int v = S.top();
+ S.pop();
+
+ if (!cont[v]) {
+ dfs(v);
+ scc++;
+ }
+ }
+
+ return scc;
+}
--
GitLab