Add clone-graph solution

Author: Jeehay28

clone-graph/Jeehay28.js

@@ -0,0 +1,68 @@
+/**
+ * // Definition for a _Node.
+ * function _Node(val, neighbors) {
+ *    this.val = val === undefined ? 0 : val;
+ *    this.neighbors = neighbors === undefined ? [] : neighbors;
+ * };
+ */
+
+/**
+ * @param {_Node} node
+ * @return {_Node}
+ */
+
+// BFS approach
+// Time Complexity: O(N + E), where N is the number of nodes and E is the number of edges.
+// Space Complexity: O(N), due to the clones map and additional storage (queue for BFS, recursion stack for DFS).
+
+var cloneGraph = function (node) {
+  if (!node) {
+    return null;
+  }
+  let clone = new Node(node.val);
+  let clones = new Map();
+  clones.set(node, clone);
+  let queue = [node];
+  while (queue.length > 0) {
+    node = queue.shift();
+    for (const neighbor of node.neighbors) {
+      if (!clones.get(neighbor)) {
+        const temp = new Node(neighbor.val);
+        clones.set(neighbor, temp);
+        queue.push(neighbor);
+      }
+      clones.get(node).neighbors.push(clones.get(neighbor));
+    }
+  }
+
+  return clone;
+};
+
+// DFS approach
+// Time Complexity: O(N + E), where N is the number of nodes and E is the number of edges.
+// Space Complexity: O(N), due to the clones map and the recursion stack.
+
+var cloneGraph = function (node) {
+  if (!node) {
+    return null;
+  }
+
+  let clones = new Map();
+
+  const dfs = (node) => {
+    if (clones.has(node)) {
+      return clones.get(node);
+    }
+    let clone = new Node(node.val);
+    clones.set(node, clone);
+
+    for (neighbor of node.neighbors) {
+      clone.neighbors.push(dfs(neighbor));
+    }
+
+    return clone;
+  };
+
+  return dfs(node);
+};
+