From b5b031db7f5ec1a3962c97328dec7e1145e499ca Mon Sep 17 00:00:00 2001
From: stefiosif <stef8iosif@gmail.com>
Date: Sat, 11 Jun 2022 19:27:03 +0300
Subject: [PATCH] Add BFS tree

---
 algorithm/bfs.h        | 62 ++++++++++++++++++++++++++++++++++++++++++
 graph/graph.h          | 21 ++++++++++++++
 test/algorithm_test.cc | 34 +++++++++++++++++++----
 test/graph_test.cc     | 40 +++++++++++++++++----------
 4 files changed, 138 insertions(+), 19 deletions(-)
 create mode 100644 algorithm/bfs.h

diff --git a/algorithm/bfs.h b/algorithm/bfs.h
new file mode 100644
index 0000000..463614f
--- /dev/null
+++ b/algorithm/bfs.h
@@ -0,0 +1,62 @@
+#ifndef BFS_H_
+#define BFS_H_
+
+#include "graph/graph.h"
+using namespace graph;
+
+#include <algorithm>
+#include <queue>
+
+namespace algo {
+
+template<typename T>
+class BFS {
+public:
+  BFS(Graph<T> G, T root) : G(G), root(root) {}
+
+  //
+  std::map<T, std::set<T>> run();
+
+  //
+  std::map<T, bool> initExplore();
+private:
+  Graph<T> G;
+  T root;
+}; 
+
+template<typename T>
+std::map<T, bool> BFS<T>::initExplore() {
+  std::map<T, bool> graphExplore;
+  for (const auto& v : G.vertices) {
+    graphExplore[v] = false;
+  }
+  return graphExplore;
+}
+
+template<typename T>
+std::map<T, std::set<T>> BFS<T>::run() {
+  std::map<T, std::set<T>> tree;
+  std::map<T, bool> graphExplore = initExplore();
+  std::queue<T> Q;
+  Q.push(root);
+  graphExplore[root] = true;
+
+  while (!Q.empty()) {
+    const auto v = Q.front();
+    Q.pop();
+
+    for (const auto& u : G.adjMatrix[v]) {
+      if (!graphExplore[u]) {
+        graphExplore[u] = true;
+        tree[v].insert(u);
+        Q.push(u);
+      }
+    }
+  }
+
+  return tree;
+}
+
+} // namespace algo
+
+#endif
\ No newline at end of file
diff --git a/graph/graph.h b/graph/graph.h
index 7e3ecf2..60efc58 100644
--- a/graph/graph.h
+++ b/graph/graph.h
@@ -23,6 +23,13 @@ public:
   // Reverse graph directions
   Graph<T> reverse();
 
+  // Number of vertices
+  std::uint16_t V();
+
+  // Number of edges
+  // TODO: Calculate bidirectional edges once
+  std::uint16_t E();
+
   // Adjacency matrix representation
   std::set<T> vertices;
   std::map<T, std::set<T>> adjMatrix;
@@ -45,6 +52,20 @@ Graph<T> Graph<T>::reverse() {
   return Graph<T>();
 }
 
+template<typename T>
+std::uint16_t Graph<T>::V() {
+  return vertices.size();
+}
+
+template<typename T>
+std::uint16_t Graph<T>::E() {
+  std::uint16_t edges = 0;
+  for (const auto& v : vertices) {
+    edges += adjMatrix[v].size();
+  }
+  return edges;
+}
+
 } // namespace graph
 
 #endif
\ No newline at end of file
diff --git a/test/algorithm_test.cc b/test/algorithm_test.cc
index e36d5d1..ae3d0ce 100644
--- a/test/algorithm_test.cc
+++ b/test/algorithm_test.cc
@@ -3,15 +3,18 @@
 #include "graph/graph.h"
 using namespace graph;
 #include "algorithm/tarjan.h"
+#include "algorithm/bfs.h"
 
-TEST_SUITE("Algorithms") {
+TEST_SUITE("Algorithm.") {
 
   TEST_CASE("Tarjan T_1") {
-
+    // 1 --> 2 --> 4 --> 1
+    //       2 --> 3 --> 5 --> 7 --> 3
+    //                   5 --> 9 --> 6 --> 8 --> 9
     Graph<std::uint16_t> G;
     G.insert(1, 2);
-    G.insert(2, 4);
     G.insert(2, 3);
+    G.insert(2, 4);
     G.insert(3, 5);
     G.insert(4, 1);
     G.insert(5, 7);
@@ -41,10 +44,12 @@ TEST_SUITE("Algorithms") {
   }
 
   TEST_CASE("Tarjan T_2") {
-
+    // 1 --> 2 --> 5 --> 7 --> 2
+    // 1 --> 4 --> 3 --> 1
+    //       4 --> 6 --> 3
     Graph<std::uint16_t> G;
-    G.insert(1, 4);
     G.insert(1, 2);
+    G.insert(1, 4);
     G.insert(2, 5);
     G.insert(3, 1);
     G.insert(4, 3);
@@ -70,4 +75,23 @@ TEST_SUITE("Algorithms") {
 
     CHECK_EQ(expected, result);
   }
+
+  TEST_CASE("BFS T_1") {
+    // 1 --> 2 --> 5 --> 7 --> 2
+    // 1 --> 4 --> 3 --> 1
+    //       4 --> 6 --> 3
+    Graph<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::BFS<std::uint16_t> bfs(G, 1);
+    auto bfsTree = bfs.run();
+  }
 }
\ No newline at end of file
diff --git a/test/graph_test.cc b/test/graph_test.cc
index 0244e0a..c038a45 100644
--- a/test/graph_test.cc
+++ b/test/graph_test.cc
@@ -1,23 +1,35 @@
 #include <doctest/doctest.h>
 
-#include "graph/graph.h"
+#include "graph/scc.h"
 using namespace graph;
+#include "algorithm/tarjan.h"
 
-TEST_SUITE("Graph test.") {
+TEST_SUITE("Graph.") {
 
-  TEST_CASE("Insertion.") {
+  TEST_CASE("SCC") {
+    // 1 --> 2 --> 4 --> 1
+    //       2 --> 3 --> 5 --> 7 --> 3
+    //                   5 --> 9 --> 6 --> 8 --> 9
     Graph<std::uint16_t> G;
-    //G.insert(1);
-    //G.insert(1, 2);
-    //G.insert(1, 4);
-    //G.insert(1, 6);
-    //G.insert(2, 4);
-    //G.insert(2, 5);
-    //G.insert(3, 4);
-    //G.insert(3, 6);
-    //G.insert(4, 6);
-    //G.insert(5, 6);
+    G.insert(1, 2);
+    G.insert(2, 3);
+    G.insert(2, 4);
+    G.insert(3, 5);
+    G.insert(4, 1);
+    G.insert(5, 7);
+    G.insert(5, 9);
+    G.insert(6, 8);
+    G.insert(7, 3);
+    G.insert(8, 9);
+    G.insert(9, 6);
+
+    algo::Tarjan<std::uint16_t> tarjan(G);
+    auto tarjanOutput = tarjan.run();
+
+    std::vector<SCC<std::uint16_t>> SCCs;
+    for (const auto& scc : tarjanOutput) {
+      SCCs.push_back(scc);
+    }
 
-    
   }
 }
\ No newline at end of file