From 268d39ba3c0c8f3658897ec6944ee16c7650cf81 Mon Sep 17 00:00:00 2001
From: kraleva <viktoriakraleva@gmail.com>
Date: Sun, 2 Apr 2023 20:44:08 +0200
Subject: [PATCH] make BFS iterative
---
.../utilities/ConnectedComponentGraph.java | 40 ++++++++++++++++++-
1 file changed, 39 insertions(+), 1 deletion(-)
diff --git a/mapbuilder/src/main/java/map/builder/utilities/ConnectedComponentGraph.java b/mapbuilder/src/main/java/map/builder/utilities/ConnectedComponentGraph.java
index 9504289..7476a18 100644
--- a/mapbuilder/src/main/java/map/builder/utilities/ConnectedComponentGraph.java
+++ b/mapbuilder/src/main/java/map/builder/utilities/ConnectedComponentGraph.java
@@ -63,6 +63,44 @@ public class ConnectedComponentGraph {
return list;
}
+ public ArrayList<Long> DFS(Long s, HashMap<Long, Boolean> visited) {
+ // Create a stack for DFS
+ Stack<Long> stack = new Stack<Long>();
+ ArrayList<Long> vertices = new ArrayList<Long>();
+
+ // Push the current source node
+ stack.push(s);
+
+ while (stack.empty() == false) {
+ // Pop a vertex from stack and print it
+ s = stack.peek();
+ stack.pop();
+
+ // Stack may contain same vertex twice. So
+ // we need to print the popped item only
+ // if it is not visited.
+ if (visited.get(s) == false) {
+ System.out.print(s + " ");
+ visited.put(s, true);
+ vertices.add(s);
+ }
+
+ // Get all adjacent vertices of the popped vertex s
+ // If a adjacent has not been visited, then push it
+ // to the stack.
+ Iterator<Long> itr = adj.get(s).iterator();
+
+ while (itr.hasNext()) {
+ Long v = itr.next();
+ if (!visited.get(v))
+ stack.push(v);
+ }
+
+ }
+
+ return vertices;
+ }
+
// Function that returns reverse (or transpose) of this ConnectedComponentGraph
public ConnectedComponentGraph getTranspose() {
ConnectedComponentGraph g = new ConnectedComponentGraph();
@@ -130,7 +168,7 @@ public class ConnectedComponentGraph {
// Print Strongly connected component of the popped vertex
if (visited.get(v) == false) {
- ArrayList<Long> component = gr.DFSUtil(v, visited);
+ ArrayList<Long> component = gr.DFS(v, visited);
if (maxLength < component.size()) {
maxLength = component.size();
largestComponent = component;
--
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