Merge pull request #196 from bT-53/patch-1

Add Kosaraju's Algorithm (SCC)

Graphs/scc_kosaraju.py

@@ -0,0 +1,45 @@
+# n - no of nodes, m - no of edges
+n, m = list(map(int,input().split()))
+
+g = [[] for i in range(n)] #graph
+r = [[] for i in range(n)] #reversed graph
+# input graph data (edges)
+for i in range(m):
+    u, v = list(map(int,input().split()))
+    g[u].append(v)
+    r[v].append(u)
+
+stack = []
+visit = [False]*n
+scc = []
+component = []
+
+def dfs(u):
+    global g, r, scc, component, visit, stack
+    if visit[u]: return
+    visit[u] = True
+    for v in g[u]:
+        dfs(v)
+    stack.append(u)
+
+def dfs2(u):
+    global g, r, scc, component, visit, stack
+    if visit[u]: return
+    visit[u] = True
+    component.append(u)
+    for v in r[u]:
+        dfs2(v)
+
+def kosaraju():
+    global g, r, scc, component, visit, stack
+    for i in range(n):
+        dfs(i)
+    visit = [False]*n
+    for i in stack[::-1]:
+        if visit[i]: continue
+        component = []
+        dfs2(i)
+        scc.append(component)
+    return scc
+
+print(kosaraju())