add 133 java, update review list

README.md

@@ -866,7 +866,7 @@
 126|[Word Ladder II](https://leetcode.com/problems/word-ladder-ii/)| [Python](./leetcode_python/Breadth-First-Search/word-ladder-ii.py) ||| Hard |complex, trick, dfs, bfs, dfs+bfs, check `# 127 Word Ladder`,`amazon` | AGAIN*** (3)
 127| [Word Ladder](https://leetcode.com/problems/word-ladder/)| [Python](./leetcode_python/Breadth-First-Search/word-ladder.py) | _O(n * d)_   | _O(d)_ | Hard/Medium |good basic, check #126 Word Ladder II, `bfs`, `UBER`, `amazon`, `M$`, `fb`| AGAIN************** (9)
 130| [Surrounded Regions](https://leetcode.com/problems/surrounded-regions/)| [Python](./leetcode_python/Breadth-First-Search/surrounded-regions.py) | _O(m + n)_ | | Medium |`bfs`, `dfs`,`union find`,good basic, `amazon`| AGAIN*********** (5)
-133| [Clone Graph](https://leetcode.com/problems/clone-graph/)| [Python](./leetcode_python/Breadth-First-Search/clone-graph.py) | _O(n)_ | _O(n)_  | Medium  |Curated Top 75, good trick, `check #138 Copy List with Random Pointer `,`graph`,`dfs`,`bfs`, copy, `UBER`, `google`,`amazon`,`fb`|  AGAIN**************** (9) (MUST)
+133| [Clone Graph](https://leetcode.com/problems/clone-graph/)| [Python](./leetcode_python/Breadth-First-Search/clone-graph.py), [Java](./leetcode_java/src/main/java/LeetCodeJava/Graph/CloneGraph.java)  | _O(n)_ | _O(n)_  | Medium  |Curated Top 75, good trick, `check #138 Copy List with Random Pointer `,`graph`,`dfs`,`bfs`, `UBER`, `google`,`amazon`,`fb`|  AGAIN**************** (9) (MUST)
 207| [Course Schedule](https://leetcode.com/problems/course-schedule/)| [Python](./leetcode_python/Breadth-First-Search/course-schedule.py), [Java](./leetcode_java/src/main/java/LeetCodeJava/BFS/CourseSchedule.java)  | _O(\|V\| + \|E\|)_   |  _O(\|E\|)_  |  Medium  |Curated Top 75, Topological Sort, backtrack, `good trick`,`dfs`, `bfs` , `amazon`,`fb`| AGAIN**************** (12) (MUST) 
 210| [Course Schedule II](https://leetcode.com/problems/course-schedule-ii/)| [Python](./leetcode_python/Breadth-First-Search/course-schedule-ii.py)    | _O(\|V\| + \|E\|)_   | _O(\|E\|)_  | Medium  |Topological Sort,check `# 207 Course Schedule ` first, `dfs`, `bfs` ,`amazon` ,`fb` | AGAIN********* (9) (again)
 261| [Graph Valid Tree](https://leetcode.com/problems/graph-valid-tree/)| [Python](./leetcode_python/Breadth-First-Search/graph-valid-tree.py)    | _O(\|V\| + \|E\|)_    | _O(\|V\| + \|E\|)_   | Medium  | Curated Top 75, AGAIN, bfs, dfs, grpah, 🔒, `graph`,`quick union`,`union find` ,`google`,`amazon`,`fb`| AGAIN************* (8)

data/progress.txt

@@ -1,3 +1,4 @@
+20230930: 133
 20230903: 654,106,105
 20230830: 200
 20230827: 131,17

data/to_review.txt

@@ -1,14 +1,19 @@
+2023-11-24 -> ['133']
+2023-11-03 -> ['133']
 2023-10-28 -> ['654,106,105']
 2023-10-24 -> ['200']
-2023-10-21 -> ['131,17']
+2023-10-21 -> ['133', '131,17']
 2023-10-16 -> ['79']
 2023-10-15 -> ['40']
 2023-10-14 -> ['90']
-2023-10-13 -> ['46']
+2023-10-13 -> ['133', '46']
+2023-10-08 -> ['133']
 2023-10-07 -> ['654,106,105', '78,39']
 2023-10-06 -> ['355']
-2023-10-05 -> ['621']
-2023-10-03 -> ['200', '973,215']
+2023-10-05 -> ['133', '621']
+2023-10-03 -> ['133', '200', '973,215']
+2023-10-02 -> ['133']
+2023-10-01 -> ['133']
 2023-09-30 -> ['131,17']
 2023-09-25 -> ['79']
 2023-09-24 -> ['654,106,105', '40']

leetcode_java/src/main/java/LeetCodeJava/Graph/CloneGraph.java

@@ -5,6 +5,17 @@
 import java.util.*;
 
 // https://leetcode.com/problems/clone-graph/
+// NOTE !!! :  Node.val is unique for each node.
+/**
+ *  Constraints:
+ *
+ * - The number of nodes in the graph is in the range [0, 100].
+ * - 1 <= Node.val <= 100
+ * - Node.val is unique for each node.
+ * - There are no repeated edges and no self-loops in the graph.
+ * - The Graph is connected and all nodes can be visited starting from the given node.
+ */
+
 
 /*
 // Definition for a Node.
@@ -28,60 +39,127 @@ public Node(int _val, ArrayList<Node> _neighbors) {
 
 public class CloneGraph {
 
+    // TODO : fix below
     // V0
-    Node clonedNode = new Node();
-    public Node cloneGraph(Node node) {
-
-        if (node == null){
+//    Node clonedNode = new Node();
+//    public Node cloneGraph(Node node) {
+//
+//        if (node == null){
+//            return node;
+//        }
+//
+//        // build map : {node_val : node_neighbors}
+//        Map<Integer, Set<Node>> map = new HashMap<>();
+//        for (Node x : node.neighbors){
+//            int _val = x.val;
+//            List<Node> _neighbors = x.neighbors;
+//            if (!map.containsKey(_val)){
+//                map.put(_val, new HashSet<>());
+//            }
+//            for (Node y : _neighbors){
+//                map.get(_val).add(y);
+//            }
+//        }
+//
+//        List<Integer> visited = new ArrayList<>();
+//        // (status) 0 : not visited, 1 : visiting, 2 : visited
+//        int status = 0;
+//        _help(node, visited, map, status);
+//        return this.clonedNode;
+//    }
+//
+//    private void _help(Node node, List<Integer> visited, Map<Integer, Set<Node>> map, int status){
+//
+//        // all nodes are visited
+//        if (visited.size() == map.keySet().size()){
+//            return;
+//        }
+//
+//        if (!visited.contains(node)){
+//            this.clonedNode = node;
+//            visited.add(node.val);
+//            if (map.get(node).isEmpty()){
+//                status = 2;
+//                map.remove(node.val);
+//            }
+//        }
+//
+//        for (Node _node : map.get(node)){
+//            // remove visiting node in map val
+//            map.get(_node.val).remove(_node);
+//            _help(_node, visited, map, 1);
+//        }
+//
+//    }
+
+    // V1
+    // IDEA : DFS
+    // https://leetcode.com/problems/clone-graph/editorial/
+    private HashMap <Node, Node> visited = new HashMap <> ();
+    public Node cloneGraph_1(Node node) {
+        if (node == null) {
             return node;
         }
 
-        // build map : {node_val : node_neighbors}
-        Map<Integer, Set<Node>> map = new HashMap<>();
-        for (Node x : node.neighbors){
-            int _val = x.val;
-            List<Node> _neighbors = x.neighbors;
-            if (!map.containsKey(_val)){
-                map.put(_val, new HashSet<>());
-            }
-            for (Node y : _neighbors){
-                map.get(_val).add(y);
-            }
+        // If the node was already visited before.
+        // Return the clone from the visited dictionary.
+        if (visited.containsKey(node)) {
+            return visited.get(node);
         }
 
-        List<Integer> visited = new ArrayList<>();
-        // (status) 0 : not visited, 1 : visiting, 2 : visited
-        int status = 0;
-        _help(node, visited, map, status);
-        return this.clonedNode;
-    }
-
-    private void _help(Node node, List<Integer> visited, Map<Integer, Set<Node>> map, int status){
+        // Create a clone for the given node.
+        // Note that we don't have cloned neighbors as of now, hence [].
+        Node cloneNode = new Node(node.val, new ArrayList());
+        // The key is original node and value being the clone node.
+        visited.put(node, cloneNode);
 
-        // all nodes are visited
-        if (visited.size() == map.keySet().size()){
-            return;
+        // Iterate through the neighbors to generate their clones
+        // and prepare a list of cloned neighbors to be added to the cloned node.
+        for (Node neighbor: node.neighbors) {
+            cloneNode.neighbors.add(cloneGraph_1(neighbor));
         }
 
-        if (!visited.contains(node)){
-            this.clonedNode = node;
-            visited.add(node.val);
-            if (map.get(node).isEmpty()){
-                status = 2;
-                map.remove(node.val);
-            }
-        }
+        // NOTE !!! after dfs, we return final result
+        return cloneNode;
+    }
 
-        for (Node _node : map.get(node)){
-            // remove visiting node in map val
-            map.get(_node.val).remove(_node);
-            _help(_node, visited, map, 1);
+    // V2
+    // IDEA : BFS
+    // https://leetcode.com/problems/clone-graph/editorial/
+    public Node cloneGraph_2(Node node) {
+        if (node == null) {
+            return node;
         }
 
-    }
+        // Hash map to save the visited node and it's respective clone
+        // as key and value respectively. This helps to avoid cycles.
+        HashMap<Node, Node> visited = new HashMap();
+
+        // Put the first node in the queue
+        LinkedList<Node> queue = new LinkedList<Node> ();
+        queue.add(node);
+        // Clone the node and put it in the visited dictionary.
+        visited.put(node, new Node(node.val, new ArrayList()));
+
+        // Start BFS traversal
+        while (!queue.isEmpty()) {
+            // Pop a node say "n" from the front of the queue.
+            Node n = queue.remove();
+            // Iterate through all the neighbors of the node "n"
+            for (Node neighbor: n.neighbors) {
+                if (!visited.containsKey(neighbor)) {
+                    // Clone the neighbor and put in the visited, if not present already
+                    visited.put(neighbor, new Node(neighbor.val, new ArrayList()));
+                    // Add the newly encountered node to the queue.
+                    queue.add(neighbor);
+                }
+                // Add the clone of the neighbor to the neighbors of the clone node "n".
+                visited.get(n).neighbors.add(visited.get(neighbor));
+            }
+        }
 
-    public static void main(String[] args) {
-        System.out.println(new Node());
+        // Return the clone of the node from visited.
+        return visited.get(node);
     }
 
 }