Update Find if Path Exists in Graph - Leetcode 1971.java

Author: gahogg

Find if Path Exists in Graph - Leetcode 1971/Find if Path Exists in Graph - Leetcode 1971.java

@@ -30,3 +30,68 @@ private boolean dfs(int node, int destination, Map<Integer, List<Integer>> graph
         return false;
     }
 }
+
+
+// Iterative DFS With Stack
+import java.util.*;
+
+public class Solution {
+    public boolean validPath(int n, int[][] edges, int source, int destination) {
+        if (source == destination) return true;
+
+        Map<Integer, List<Integer>> graph = new HashMap<>();
+        for (int[] edge : edges) {
+            graph.computeIfAbsent(edge[0], k -> new ArrayList<>()).add(edge[1]);
+            graph.computeIfAbsent(edge[1], k -> new ArrayList<>()).add(edge[0]);
+        }
+
+        Set<Integer> seen = new HashSet<>();
+        Stack<Integer> stack = new Stack<>();
+        stack.push(source);
+        seen.add(source);
+
+        while (!stack.isEmpty()) {
+            int node = stack.pop();
+            if (node == destination) return true;
+            for (int neighbor : graph.getOrDefault(node, Collections.emptyList())) {
+                if (!seen.contains(neighbor)) {
+                    seen.add(neighbor);
+                    stack.push(neighbor);
+                }
+            }
+        }
+        return false;
+    }
+}
+
+// BFS With Queue
+import java.util.*;
+
+public class Solution {
+    public boolean validPath(int n, int[][] edges, int source, int destination) {
+        if (source == destination) return true;
+
+        Map<Integer, List<Integer>> graph = new HashMap<>();
+        for (int[] edge : edges) {
+            graph.computeIfAbsent(edge[0], k -> new ArrayList<>()).add(edge[1]);
+            graph.computeIfAbsent(edge[1], k -> new ArrayList<>()).add(edge[0]);
+        }
+
+        Set<Integer> seen = new HashSet<>();
+        Queue<Integer> queue = new LinkedList<>();
+        queue.offer(source);
+        seen.add(source);
+
+        while (!queue.isEmpty()) {
+            int node = queue.poll();
+            if (node == destination) return true;
+            for (int neighbor : graph.getOrDefault(node, Collections.emptyList())) {
+                if (!seen.contains(neighbor)) {
+                    seen.add(neighbor);
+                    queue.offer(neighbor);
+                }
+            }
+        }
+        return false;
+    }
+}