Move headers into include folder and add single header to include all reachability algorithms

include/algorithm/breadth_first_search.h

@@ -0,0 +1,80 @@
+#ifndef BREADTH_FIRST_SEARCH_H_
+#define BREADTH_FIRST_SEARCH_H_
+
+#include <map>
+#include <set>
+#include <queue>
+
+using namespace graph;
+
+namespace algo {
+
+template<typename T>
+class BreadthFirstSearch {
+public:
+  BreadthFirstSearch() = default;
+
+  BreadthFirstSearch(std::unordered_map<T, std::unordered_set<T>> adjList)
+    : adjList(adjList) {}
+
+  // Traverse whole graph using the BFS search, and save the tree graph
+  // which is created when visiting new vertices (Breadth First Tree)
+  std::unordered_map<T, std::unordered_set<T>> execute(const T& root);
+
+  // Search if target vertex exists in graph
+  bool query(const T& root, const T& target);
+private:
+  // Represents the graph on which the algorithm will be executed
+  std::unordered_map<T, std::unordered_set<T>> adjList;
+}; 
+
+template<typename T>
+std::unordered_map<T, std::unordered_set<T>> BreadthFirstSearch<T>::execute(const T& root) {
+  std::unordered_map<T, std::unordered_set<T>> tree;
+  std::unordered_map<T, bool> visited;
+  std::queue<T> Q;
+  Q.push(root);
+  visited[root] = true;
+
+  while (!Q.empty()) {
+    const auto v = Q.front();
+    Q.pop();
+
+    for (const auto& u : adjList[v]) {
+      if (!visited[u]) {
+        visited[u] = true;
+        tree[v].insert(u);
+        tree[u];
+        Q.push(u);
+      }
+    }
+  }
+  return tree;
+}
+
+template<typename T>
+bool BreadthFirstSearch<T>::query(const T& root, const T& target) {
+  std::unordered_map<T, bool> visited;
+  std::queue<T> Q;
+  Q.push(root);
+  visited[root] = true;
+
+  while (!Q.empty()) {
+    const auto v = Q.front();
+    Q.pop();
+
+    if (v == target) return true;
+
+    for (const auto& u : adjList[v]) {
+      if (!visited[u]) {
+        visited[u] = true;
+        Q.push(u);
+      }
+    }
+  }
+  return false;
+}
+
+} // namespace algo
+
+#endif