clone graph solution

Author: wad-jangjaejeong

clone-graph/jaejeong1.java

@@ -0,0 +1,56 @@
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Queue;
+
+// Definition for a Node.
+class Node {
+  public int val;
+  public List<Node> neighbors;
+  public Node() {
+    val = 0;
+    neighbors = new ArrayList<Node>();
+  }
+  public Node(int _val) {
+    val = _val;
+    neighbors = new ArrayList<Node>();
+  }
+  public Node(int _val, ArrayList<Node> _neighbors) {
+    val = _val;
+    neighbors = _neighbors;
+  }
+}
+
+
+class Solution {
+  // 풀이: BFS 방식으로 그래프를 순회하면서 현재 노드에 연결된 노드들을 복제 여부에 따라 복제 또는 연결 처리해준다
+  // TC: O(N)
+  // SC: O(N)
+  public Node cloneGraph(Node node) {
+    if (node == null) {
+      return null;
+    }
+
+    Map<Node, Node> cloneMap = new HashMap<>();
+    Node clone = new Node(node.val);
+    cloneMap.put(node, clone);
+
+    Queue<Node> queue = new LinkedList<>();
+    queue.add(node);
+
+    while (!queue.isEmpty()) {
+      Node current = queue.poll();
+
+      for (Node neighbor : current.neighbors) {
+        if (!cloneMap.containsKey(neighbor)) {
+          cloneMap.put(neighbor, new Node(neighbor.val));
+          queue.add(neighbor);
+        }
+        cloneMap.get(current).neighbors.add(cloneMap.get(neighbor));
+      }
+    }
+    return clone;
+  }
+}