Add roditty and zwick class

algorithm/dmscc.h

@@ -1,19 +0,0 @@
-#ifndef DMSCC_H_
-#define DMSCC_H_
-
-#include "graph/graph.h"
-using namespace graph;
-#include "tarjan.h"
-
-namespace algo {
-
-// A randomized decremental algorithm for maintaining SCCs
-template<typename T>
-class DMSCC {
-public:
-  DMSCC() = default;
-};
-
-}; // namespace algo
-
-#endif

algorithm/roditty_zwick.h

@@ -0,0 +1,55 @@
+#ifndef RODITTY_ZWICK_H_
+#define RODITTY_ZWICK_H_
+
+#include "graph/digraph.h"
+#include "graph/scc.h"
+#include "algorithm/tarjan.h"
+#include "algorithm/bfs.h"
+
+#include <vector>
+
+using namespace graph;
+
+namespace algo {
+
+// A randomized decremental algorithm for maintaining SCCs
+template<typename T>
+class RodittyZwick {
+public:
+  RodittyZwick(Digraph<T> G) : G(G) {}
+
+  //
+  void sccDecrementalMaintenance();
+
+  //
+  void tcDecrementalMaintenance();
+private:
+  Digraph<T> G;
+};
+
+template<typename T>
+void RodittyZwick<T>::sccDecrementalMaintenance() {
+  std::map<T, T> A;
+  Tarjan<T> tarjan(G);
+
+  auto sccs = tarjan.run();
+
+  for (auto& scc : sccs) {
+    const auto& root = scc.representative();
+    BFS<T> bfs(scc);
+    auto spt = bfs.run(root);
+    for (const auto& vertex : scc.vertices) {
+      A[vertex] = root;
+    }
+
+  }
+}
+
+template<typename T>
+void RodittyZwick<T>::tcDecrementalMaintenance() {
+
+}
+
+}; // namespace algo
+
+#endif

graph/digraph.h

@@ -4,6 +4,7 @@
 #include "graph.h"
 
 #include <algorithm>
+#include <ranges>
 
 namespace graph {
 
@@ -12,10 +13,19 @@ class Digraph : public Graph<T> {
 public:
   Digraph() = default;
 
+  Digraph(std::map<T, std::set<T>> digraph);
+
   // Reverse graph directions
   Digraph<T> reverse();
 };
 
+template<typename T>
+Digraph<T>::Digraph(std::map<T, std::set<T>> digraph) {
+  Graph<T>::adjMatrix = digraph;
+  auto kv = std::views::keys(Graph<T>::adjMatrix);
+  Graph<T>::vertices = std::set<T>{ kv.begin(), kv.end() };
+}
+
 template<typename T>
 Digraph<T> Digraph<T>::reverse() {
   return Digraph<T>();

graph/scc.h

@@ -12,8 +12,13 @@ class SCC : public Graph<T> {
 public:
   SCC(std::map<T, std::set<T>> scc);
 
+  //
+  T representative() { return proxy; };
 private:
-  T root;
+  // Each SCC has a representative vertex that helps
+  // answer strong connectivity queries in O(1) time
+  T proxy;
+
 };
 
 template<typename T>
@@ -21,7 +26,7 @@ SCC<T>::SCC(std::map<T, std::set<T>> scc) {
   Graph<T>::adjMatrix = scc;
   auto kv = std::views::keys(Graph<T>::adjMatrix);
   Graph<T>::vertices = std::set<T>{ kv.begin(), kv.end() };
-  root = scc.begin()->first;
+  proxy = scc.begin()->first;
 }
 
 }; // namespace graph

test/algorithm_test.cc

@@ -4,6 +4,7 @@
 #include "graph/scc.h"
 #include "algorithm/tarjan.h"
 #include "algorithm/bfs.h"
+#include "algorithm/roditty_zwick.h"
 
 using namespace graph;
 
@@ -91,8 +92,8 @@ TEST_SUITE("Algorithm") {
     G.insert(6, 3);
     G.insert(7, 2);
 
-    algo::BFS<std::uint16_t> bfs(G, 1);
-    auto tree = bfs.run();
+    algo::BFS<std::uint16_t> bfs(G);
+    auto tree = bfs.run(1);
 
     /*std::map<std::uint16_t, std::set<std::uint16_t>> exp = {
       {1, {2, 4}},
@@ -111,6 +112,25 @@ TEST_SUITE("Algorithm") {
       {5, {7}}
     };
 
-    CHECK_EQ(tree, exp);
+    CHECK_EQ(tree.adjMatrix, exp);
+  }
+
+  TEST_CASE("Roditty Zwick A1 T1 ") {
+    // 1 --> 2 --> 5 --> 7 --> 2
+    // 1 --> 4 --> 3 --> 1
+    //       4 --> 6 --> 3
+    Digraph<std::uint16_t> G;
+    G.insert(1, 2);
+    G.insert(1, 4);
+    G.insert(2, 5);
+    G.insert(3, 1);
+    G.insert(4, 3);
+    G.insert(4, 6);
+    G.insert(5, 7);
+    G.insert(6, 3);
+    G.insert(7, 2);
+
+    algo::RodittyZwick<std::uint16_t> rz(G);
+    rz.sccDecrementalMaintenance();
   }
 }