133. Clone Graph (Graph, Map; DFS)

標籤：

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         /          \_/

struct UndirectedGraphNode {    int label;    vector<UndirectedGraphNode *> neighbors;    UndirectedGraphNode(int x) : label(x) {};};class Solution {public:    UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {        if(!node) return NULL;        UndirectedGraphNode *current;        map<UndirectedGraphNode*,UndirectedGraphNode*> flag; //前一個元素是節點在原Graph中的地址，後一個元素是節點在新拷貝的圖中的位置        UndirectedGraphNode *root = cloneNode(node,flag);        return root;    }        UndirectedGraphNode * cloneNode(UndirectedGraphNode *source, map<UndirectedGraphNode*,UndirectedGraphNode*> &flag)    {        if(flag.find(source)!= flag.end()) return flag[source];        //如果map中沒有該節點，那麼建立該節點        UndirectedGraphNode *target = new UndirectedGraphNode(source->label);         flag[source] = target;        for(vector<UndirectedGraphNode *>::iterator it = source->neighbors.begin(); it < source->neighbors.end(); it++ )        {            UndirectedGraphNode *newRoot = cloneNode(*it, flag); //深度優先，先遞迴處理它的某一個鄰居，再處理其他鄰居            target->neighbors.push_back(newRoot);        }        return target; //返回已經處理好的節點    }};

 

133. Clone Graph (Graph, Map; DFS)