solves #133 in java

Author: anishLearnsToCode

Diff for: README.md

@@ -119,7 +119,7 @@
 | 129  | [Sum Root to Leaf Numbers](https://leetcode.com/problems/sum-root-to-leaf-numbers)                                                                        |                                                              [![Java](assets/java.png)](src/SumRootToLeafNumbers.java)                                                               |                                                                                                                                   |
 | 130  | [Surrounded Regions](https://leetcode.com/problems/surrounded-regions)                                                                                    |                                                                [![Java](assets/java.png)](src/SurroundedRegions.java)                                                                |                                                                                                                                   |
 | 131  | [Palindrome Partitioning](https://leetcode.com/problems/palindrome-partitioning)                                                                          |                                                             [![Java](assets/java.png)](src/PalindromePartitioning.java)                                                              |                                                                                                                                   |
-| 133  | [Clone Graph](https://leetcode.com/problems/clone-graph)                                                                                                  |                                                                                                                                                                                      |                                                                                                                                   |
+| 133  | [Clone Graph](https://leetcode.com/problems/clone-graph)                                                                                                  |                                                                   [![Java](assets/java.png)](src/CloneGraph.java)                                                                    |                                                                                                                                   |
 | 134  | [Gas Station](https://leetcode.com/problems/gas-station)                                                                                                  |                                                                                                                                                                                      |                                                                                                                                   |
 | 136  | [Single Number](https://leetcode.com/problems/single-number)                                                                                              |                                      [![Java](assets/java.png)](src/SingleNumber.java) [![Python](assets/python.png)](python/single_number.py)                                       |                                                                                                                                   |
 | 137  | [Single Number II](https://leetcode.com/problems/single-number-ii)                                                                                        |                                                                                                                                                                                      |                                                                                                                                   |

Diff for: src/CloneGraph.java

@@ -0,0 +1,59 @@
+// https://leetcode.com/problems/clone-graph
+// T: O(n)
+// S: O(n)
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+public class CloneGraph {
+    private static final class Node {
+        public int val;
+        public List<Node> neighbors;
+
+        public Node() {
+            val = 0;
+            neighbors = new ArrayList<>();
+        }
+
+        public Node(int val) {
+            this.val = val;
+            neighbors = new ArrayList<>();
+        }
+
+        public Node(int val, ArrayList<Node> neighbors) {
+            this.val = val;
+            this.neighbors = neighbors;
+        }
+    }
+
+    public Node cloneGraph(Node node) {
+        if (node == null) return null;
+        final Map<Integer, Node> graph = new HashMap<>();
+        cloneGraph(node, new HashSet<>(), graph);
+        return graph.get(node.val);
+    }
+
+    private void cloneGraph(Node node, Set<Integer> visited, Map<Integer, Node> newGraph) {
+        if (node == null) return;
+        if (visited.contains(node.val)) return;
+        visited.add(node.val);
+
+        Node current = getNode(newGraph, node.val);
+        for (Node adjacent : node.neighbors) {
+            Node newNeighbour = getNode(newGraph, adjacent.val);
+            current.neighbors.add(newNeighbour);
+            cloneGraph(adjacent, visited, newGraph);
+        }
+    }
+
+    private Node getNode(Map<Integer, Node> graph, int value) {
+        if (graph.containsKey(value)) return graph.get(value);
+        Node node = new Node(value);
+        graph.put(value, node);
+        return node;
+    }
+}

Diff for: src/HelloWorld.java

@@ -1,12 +1,4 @@
-import java.util.Map;
-
-import static java.util.Map.entry;
-
 public class HelloWorld {
     public static void main(String[] args) {
-        Map<String, Object> map = Map.of(
-                "hello", null,
-                "", null
-        );
     }
 }