BFS.cpp

Author: lxylxy123456

BFS.cpp

@@ -0,0 +1,130 @@
+//  
+//  algorithm - some algorithms in "Introduction to Algorithms", third edition
+//  Copyright (C) 2018  lxylxy123456
+//  
+//  This program is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU Affero General Public License as
+//  published by the Free Software Foundation, either version 3 of the
+//  License, or (at your option) any later version.
+//  
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU Affero General Public License for more details.
+//  
+//  You should have received a copy of the GNU Affero General Public License
+//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+//  
+
+#ifndef MAIN
+#define MAIN
+#define MAIN_BFS
+#endif
+
+#ifndef FUNC_BFS
+#define FUNC_BFS
+
+#include <cassert>
+#include "utils.h"
+
+#include "Queue.cpp"
+#include "Graph.cpp"
+
+const size_t INF = -1; 
+
+enum BFSColor { white, gray, black }; 
+
+template <typename T>
+class BFSInfo {
+	public:
+		BFSInfo(): color(white), d(INF) {}
+		BFSInfo(enum BFSColor c, size_t dist): color(c), d(dist) {}
+		BFSInfo(enum BFSColor c, size_t dist, T p): color(c), d(dist), pi(p) {}
+		enum BFSColor color; 
+		size_t d; 
+		T pi; 
+}; 
+
+template <typename GT, typename T>
+void BFS(GT& G, T s, umap<T, BFSInfo<T>>& ans) {
+	for (auto i = G.V.begin(); i != G.V.end(); i++) {
+		if (*i == s)
+			ans[*i] = BFSInfo<T>(gray, 0); 
+		else
+			ans[*i] = BFSInfo<T>(); 
+	}
+	Queue<T> Q(G.V.size()); 
+	Q.Enqueue(s); 
+	while (!Q.Empty()) {
+		T u = Q.Dequeue(); 
+		for (auto i = G.edges_from(u); !i.end(); i++)
+			if (ans[i.d()].color == white) {
+				ans[i.d()].color = gray; 
+				ans[i.d()].d = ans[u].d + 1; 
+				ans[i.d()].pi = u; 
+				Q.Enqueue(i.d()); 
+			}
+		ans[u].color = black; 
+	}
+}
+
+template <typename T>
+void PrintPath(T s, T v, umap<T, BFSInfo<T>> inf, std::vector<T>& ans) {
+	if (v == s)
+		ans.push_back(v); 
+	else if (inf[v].d != INF) {
+		PrintPath(s, inf[v].pi, inf, ans); 
+		ans.push_back(v); 
+	}
+}
+#endif
+
+#ifdef MAIN_BFS
+int main(int argc, char *argv[]) {
+	const size_t v = get_argv(argc, argv, 1, 5); 
+	const size_t e = get_argv(argc, argv, 2, 10); 
+	const bool dir = get_argv(argc, argv, 3, 0); 
+	GraphAdjList<size_t> G(dir); 
+	random_graph(G, v, e); 
+	umap<size_t, BFSInfo<size_t>> inf; 
+	size_t s = 0; 
+	BFS(G, s, inf); 
+	auto f1 = [inf](size_t v) mutable {
+		BFSInfo<size_t>& i = inf[v]; 
+		std::cout << " ["; 
+		switch (i.color) {
+			case white: 
+				break; 
+			case black: 
+				std::cout << "color=black style=filled fontcolor=white "; 
+				break; 
+			case gray: 
+				std::cout << "color=gray style=filled "; 
+				break; 
+		}
+		std::cout << "label=\"" << v << "\\n"; 
+		if (i.d == 0)
+			std::cout << "d = " << i.d; 
+		else if (i.d == INF)
+			std::cout << "d = INF"; 
+		else
+			std::cout << "d = " << i.d << "; pi = " << i.pi; 
+		std::cout << "\""; 
+		std::cout << "]"; 
+		return true; 
+	}; 
+	auto f2 = [dir](Edge<size_t> e) {}; 
+	graphviz(G, f1, f2); 
+	for (auto i = G.V.begin(); i != G.V.end(); i++) {
+		std::vector<size_t> ans; 
+		PrintPath(s, *i, inf, ans); 
+		std::cout << *i << '\t'; 
+		if (ans.size())
+			output_integers(ans); 
+		else
+			std::cout << "no path from " << s << " exists" << std::endl; 
+	}
+	return 0; 
+}
+#endif
+

Graph.cpp

@@ -26,11 +26,10 @@
 
 #include <unordered_set>
 #include <unordered_map>
-#include <iterator>
 #include "utils.h"
 
-#define set typename std::unordered_set
-#define map typename std::unordered_map
+#define uset typename std::unordered_set
+#define umap typename std::unordered_map
 
 template <typename T>
 class Edge {
@@ -49,7 +48,7 @@ class Edge {
 template <typename T>
 class EdgeIteratorAL1 {
 	public:
-		EdgeIteratorAL1(map<T, set<T>>& E, bool direction): dir(direction) {
+		EdgeIteratorAL1(umap<T, uset<T>>& E, bool direction): dir(direction) {
 			mbegin = E.begin(); 
 			mend = E.end(); 
 			sbegin = mbegin->second.begin(); 
@@ -83,14 +82,14 @@ class EdgeIteratorAL1 {
 		T s() { return mbegin->first; }
 		T d() { return *sbegin; }
 		bool dir; 
-		map<T, set<T>>::iterator mbegin, mend; 
-		set<T>::iterator sbegin, send; 
+		umap<T, uset<T>>::iterator mbegin, mend; 
+		uset<T>::iterator sbegin, send; 
 }; 
 
 template <typename T>
 class EdgeIteratorAL2 {
 	public:
-		EdgeIteratorAL2(T ss, set<T>& E, bool direction): S(ss), dir(direction){
+		EdgeIteratorAL2(T ss, uset<T>& E, bool direction): S(ss),dir(direction){
 			sbegin = E.begin(); 
 			send = E.end(); 
 		}
@@ -108,13 +107,13 @@ class EdgeIteratorAL2 {
 		T d() { return *sbegin; }
 		T S; 
 		bool dir; 
-		set<T>::iterator sbegin, send; 
+		uset<T>::iterator sbegin, send; 
 }; 
 
 template <typename T>
 class EdgeIteratorAM1 {
 	public:
-		EdgeIteratorAM1(map<T, map<T, bool>>& E, bool direction) {
+		EdgeIteratorAM1(umap<T, umap<T, bool>>& E, bool direction) {
 			dir = direction; 
 			mbegin = E.begin(); 
 			mend = E.end(); 
@@ -149,14 +148,14 @@ class EdgeIteratorAM1 {
 		T s() { return mbegin->first; }
 		T d() { return sbegin->first; }
 		bool dir; 
-		map<T, map<T, bool>>::iterator mbegin, mend; 
-		map<T, bool>::iterator sbegin, send; 
+		umap<T, umap<T, bool>>::iterator mbegin, mend; 
+		umap<T, bool>::iterator sbegin, send; 
 }; 
 
 template <typename T>
 class EdgeIteratorAM2 {
 	public:
-		EdgeIteratorAM2(T ss, map<T, bool>& E, bool direction): S(ss) {
+		EdgeIteratorAM2(T ss, umap<T, bool>& E, bool direction): S(ss) {
 			dir = direction; 
 			sbegin = E.begin(); 
 			send = E.end(); 
@@ -181,7 +180,7 @@ class EdgeIteratorAM2 {
 		T d() { return sbegin->first; }
 		T S; 
 		bool dir; 
-		map<T, bool>::iterator sbegin, send; 
+		umap<T, bool>::iterator sbegin, send; 
 }; 
 
 template <typename T>
@@ -194,11 +193,15 @@ class Graph {
 			V.insert(u); 
 			return true; 
 		}
+		void add_edge(Edge<T> e) {
+			this->add_edge(e.s, e.d); 
+		}
 		virtual void add_edge(T, T) = 0; 
 		virtual bool is_edge(T u, T v) = 0; 
 		virtual ~Graph() {}
+		typedef T vertix_type; 
 		bool dir; 
-		set<T> V; 
+		uset<T> V; 
 }; 
 
 template <typename T>
@@ -222,7 +225,7 @@ class GraphAdjList: public Graph<T> {
 			return EdgeIteratorAL2<T>(s, E[s], this->dir); 
 		}
 		virtual ~GraphAdjList() {}
-		map<T, set<T>> E; 
+		umap<T, uset<T>> E; 
 }; 
 
 template <typename T>
@@ -256,7 +259,7 @@ class GraphAdjMatrix: public Graph<T> {
 			return EdgeIteratorAM2<T>(s, E[s], this->dir); 
 		}
 		virtual ~GraphAdjMatrix() {}
-		map<T, map<T, bool>> E; 
+		umap<T, umap<T, bool>> E; 
 }; 
 
 template <typename T>
@@ -269,44 +272,43 @@ void random_graph(Graph<T>& G, T v, T e) {
 		G.add_edge(d[2 * i], d[2 * i + 1]); 
 }
 
-template <typename T>
-void graphviz(T& G) {
+template <typename T, typename F1, typename F2>
+void graphviz(T& G, F1 f1, F2 f2) {
 	if (G.dir)
 		std::cout << "digraph G {" << std::endl; 
 	else
 		std::cout << "graph G {" << std::endl; 
 	std::cout << '\t'; 
-	for (auto i = G.V.begin(); i != G.V.end(); i++)
-		std::cout << *i << "; "; 
+	for (auto i = G.V.begin(); i != G.V.end(); i++) {
+		std::cout << *i; 
+		if (f1(*i))
+			std::cout << "; \n\t"; 
+		else
+			std::cout << "; "; 
+	}
 	std::cout << std::endl; 
 	for (auto i = G.all_edges(); !i.end(); i++)
-		if (G.dir || i.s() < i.d())
-			std::cout << '\t' << *i << "; " << std::endl; 
+		if (G.dir || i.s() < i.d()) {
+			std::cout << '\t' << *i; 
+			f2(*i); 
+			std::cout << "; " << std::endl; 
+		}
 	std::cout << "}" << std::endl; 
 }
+
+template <typename T>
+void graphviz(T& G) {
+	auto f1 = [](typename T::vertix_type v) { return false; }; 
+	auto f2 = [](Edge<typename T::vertix_type>) {}; 
+	graphviz(G, f1, f2); 
+}
 #endif
 
 #ifdef MAIN_Graph
-int main(int argc, char *argv[]) {
-	const size_t v = get_argv(argc, argv, 1, 5); 
-	const size_t e = get_argv(argc, argv, 2, 10); 
-	for (size_t dir = 0; dir <= 1; dir++) {
-		GraphAdjList<size_t> G(dir); 
-		random_graph(G, v, e); 
-		for (auto i = G.all_edges(); !i.end(); i++)
-			std::cout << *i << std::endl; 
-		std::cout << std::endl; 
-		for (auto i = G.V.begin(); i != G.V.end(); i++) {
-			std::cout << *i << std::endl; 
-			for (auto j = G.edges_from(*i); !j.end(); j++)
-				std::cout << '\t' << *j << std::endl; 
-		}
-		std::cout << std::endl; 
-		graphviz(G); 
-		std::cout << std::endl; 
-	}
+template <typename T>
+void graph_test(const size_t v, const size_t e) {
 	for (size_t dir = 0; dir <= 1; dir++) {
-		GraphAdjMatrix<size_t> G(dir); 
+		T G(dir); 
 		random_graph(G, v, e); 
 		for (auto i = G.all_edges(); !i.end(); i++)
 			std::cout << *i << std::endl; 
@@ -320,6 +322,13 @@ int main(int argc, char *argv[]) {
 		graphviz(G); 
 		std::cout << std::endl; 
 	}
+}
+
+int main(int argc, char *argv[]) {
+	const size_t v = get_argv(argc, argv, 1, 5); 
+	const size_t e = get_argv(argc, argv, 2, 10); 
+	graph_test<GraphAdjList<size_t>>(v, e); 
+	graph_test<GraphAdjMatrix<size_t>>(v, e); 
 	return 0; 
 }
 #endif

Queue.cpp

@@ -46,6 +46,9 @@ class Queue {
 				head = 0; 
 			return ans; 
 		}
+		bool Empty() {
+			return head == tail; 
+		}
 		~Queue() { delete [] data; }
 	private:
 		size_t head, tail, length; 
@@ -59,6 +62,7 @@ int main(int argc, char *argv[]) {
 	Queue<int> S(n); 
 	std::cout << "d: dequeue" << std::endl; 
 	std::cout << "e: enqueue" << std::endl; 
+	std::cout << "E: empty" << std::endl; 
 	std::cout << "q: quit" << std::endl; 
 	while (true) {
 		char c; int x; 
@@ -76,6 +80,9 @@ int main(int argc, char *argv[]) {
 			case 'd': 
 				std::cout << S.Dequeue() << std::endl; 
 				break; 
+			case 'E': 
+				std::cout << std::boolalpha << S.Empty() << std::endl; 
+				break; 
 			case 'q': 
 				return 0; 
 		}

README.md

@@ -144,6 +144,8 @@
 | 21 | DisjointSet.cpp				| Union									|  571 |
 | 21 | DisjointSet.cpp				| Link									|  571 |
 | 21 | DisjointSet.cpp				| Find Set								|  571 |
+| 22 | BFS.cpp						| BFS									|  595 |
+| 22 | BFS.cpp						| Print Path							|  601 |
 
 # Supplementary Files
 * `utils.h`: Utils
@@ -152,3 +154,4 @@
 # Supplementary Programs
 * `include_check.py`: identifies unnecessary includes
 * `vEB_check.py`: compare results of `ProtovEB.cpp` and `vEB.cpp`
+* `dot.sh`: generate a graphviz graph from stdin

dot.sh

@@ -0,0 +1,12 @@
+mkdir /tmp/.dot.sh/ 2> /dev/null
+
+if [ $# == 0 ]; then
+	A=`mktemp /tmp/.dot.sh/XXXXXXXX.dot`
+	cat > $A
+else
+	A=$1
+fi
+
+B=`mktemp /tmp/.dot.sh/XXXXXXXX.png`
+dot $A -Tpng -o $B && gnome-open $B 2> /dev/null > /dev/null
+

include_check.py

@@ -18,7 +18,7 @@
 				assert 'std::invalid_argument' in a
 			elif j == 'map' :
 				assert 'std::map' in a or 'std::pair' in a
-			elif j in ['list', 'set'] :
+			elif j in ['list', 'set', 'unordered_set', 'unordered_map'] :
 				assert 'std::' + j in a
 			else :
 				assert(False)