[LeetCode] 133. Clone Graph

轉自LeetCode

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 #.

1. First node is labeled as 0. Connect node 0 to both nodes 1 and 2.
2. Second node is labeled as 1. Connect node 1 to node 2.
3. 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>
這題的題意其實就是要做 deep copy，即要完整複製一份 undirected graph

有DFS和BFS兩種解法，這次使用 DFS 來解

想法如下

• 因為題目有說，每個 label 都是唯一的，所以使用一個 hash map 來記錄已經創好的 node，避免創建出多餘的node

• 用 DFS 去處理 neighbors 的拷貝。先把一條完整的 path 串完，再回頭找下一條

code 如下(參考資料)
c++

kotlin