Add clone-graph solution in TS

Author: Jeehay28

clone-graph/Jeehay28.ts

@@ -0,0 +1,67 @@
+class _Node {
+  val: number;
+  neighbors: _Node[];
+
+  constructor(val?: number, neighbors?: _Node[]) {
+    this.val = val === undefined ? 0 : val;
+    this.neighbors = neighbors === undefined ? [] : neighbors;
+  }
+}
+
+// TC: O(V + E), where V is the number of vertices and E is the number of edges
+// SC: O(V + E)
+function cloneGraph(node: _Node | null): _Node | null {
+  // 1: [2, 4]
+  // 2: [1, 3]
+  // 3: [2, 4]
+  // 4: [1, 3]
+
+  const clones = new Map<_Node, _Node>();
+  // original Node: cloned Node
+
+  if (!node) return null;
+
+  const dfs = (node: _Node) => {
+    if (clones.has(node)) {
+      return clones.get(node);
+    }
+
+    const clone = new _Node(node.val);
+    clones.set(node, clone);
+
+    for (const nei of node.neighbors) {
+      clone.neighbors.push(dfs(nei)!);
+    }
+
+    return clone;
+  };
+
+  return dfs(node)!;
+}
+
+
+// TC: O(V + E)
+// SC: O(V + E)
+// function cloneGraph(node: _Node | null): _Node | null {
+//   if (!node) return null;
+
+//   const clone: _Node = new _Node(node.val);
+//   const clones = new Map<_Node, _Node>();
+//   clones.set(node, clone);
+//   const queue: _Node[] = [node]; // BFS -> use queue
+
+//   while (queue.length > 0) {
+//     const node = queue.shift()!;
+//     for (const nei of node.neighbors) {
+//       if (!clones.has(nei)) {
+//         clones.set(nei, new _Node(nei.val));
+//         queue.push(nei);
+//       }
+//       clones.get(node)!.neighbors.push(clones.get(nei)!);
+//     }
+//   }
+
+//   return clone;
+// }
+
+