133. Clone Graph

Problem

Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.

OJ's undirected graph serialization:

Nodes are labeled uniquely.

We use # as a separator for each node, and , as a separator for node label and each neighbor of the node.

As an example, consider the serialized graph {0,1,2#1,2#2,2}.

The graph has a total of three nodes, and therefore contains three parts as separated by #.

• First node is labeled as 0. Connect node 0 to both nodes 1 and 2.
• Second node is labeled as 1. Connect node 1 to node 2.
• Third node is labeled as 2. Connect node 2 to node 2 (itself), thus forming a self-cycle.

Visually, the graph looks like the following:

 1 / \ / \ 0 --- 2 / \ \_/ 

Solution

/** * Definition for undirected graph. * function UndirectedGraphNode(label) { * this.label = label; * this.neighbors = []; // Array of UndirectedGraphNode * } */ /** * @param {UndirectedGraphNode} graph * @return {UndirectedGraphNode} */ var cloneGraph = function(graph) { return clone(graph, {}); }; var clone = function (node, map) { if (!node) return null; if (map[node.label]) return map[node.label]; var cloneNode = new UndirectedGraphNode(node.label); map[node.label] = cloneNode; for (var i = 0; i < node.neighbors.length; i++) { cloneNode.neighbors.push(clone(node.neighbors[i], map)); } return cloneNode; }; 

Explain:

不用管描述里的 # , 什么的，题意就是复制一个无向图，不要想复杂了。

注意有重复节点的话，存个引用就行，用哈希表判断是否重复。

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).