solutions/0133-clone-graph.js

/**
 * 133. Clone Graph
 * https://leetcode.com/problems/clone-graph/
 * Difficulty: Medium
 *
 * Given a reference of a node in a connected undirected graph.
 * Return a deep copy (clone) of the graph.
 * Each node in the graph contains a value (int) and a list (List[Node]) of its neighbors.
 *
 * Test case format:
 * - For simplicity, each node's value is the same as the node's index (1-indexed).
 *   For example, the first node with val == 1, the second node with val == 2, and so on.
 *   The graph is represented in the test case using an adjacency list.
 *
 * - An adjacency list is a collection of unordered lists used to represent a finite graph.
 *   Each list describes the set of neighbors of a node in the graph.
 *
 * - The given node will always be the first node with val = 1. You must return the copy of
 *   the given node as a reference to the cloned graph.
 */

/**
 * // Definition for a Node.
 * function Node(val, neighbors) {
 *    this.val = val === undefined ? 0 : val;
 *    this.neighbors = neighbors === undefined ? [] : neighbors;
 * };
 */

/**
 * @param {Node} node
 * @return {Node}
 */
var cloneGraph = function(node) {
  const map = new Map();
  return node && cloneNode(node, map);
};

function cloneNode(node, map) {
  const cloned = new Node(node.val, node.neighbors);
  map.set(node.val, cloned);

  cloned.neighbors = node.neighbors && node.neighbors.map(n => {
    return map.get(n.val) || cloneNode(n, map);
  });

  return cloned;
}