Leetcode#133 Clone Graph

原题地址

方法I，DFS

一边遍历一边复制

借助辅助map保存已经复制好了的节点

对于原图中每个节点，如果已经复制过了，直接返回新节点的地址，如果没复制过，则复制并加入map中，接着依次递归复制其兄弟。

代码：

map<UndirectedGraphNode *, UndirectedGraphNode *> old2new;

UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
        if (!node)
            return NULL;
        if (old2new.find(node) != old2new.end())
            return old2new[node];
        
        UndirectedGraphNode *newNode = new UndirectedGraphNode(node->label);
        old2new.insert(pair<UndirectedGraphNode *, UndirectedGraphNode *>(node, newNode));
        for (auto n : node->neighbors)
            newNode->neighbors.push_back(cloneGraph(n));
        return newNode;
}

方法II，BFS

一边遍历一边复制

同样借助一个辅助map保存复制过的节点，还需要一个set保存已经遍历过的节点

代码：

UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
         if (!node)
            return NULL;
            
         map<UndirectedGraphNode *, UndirectedGraphNode *> old2new;
         unordered_set<UndirectedGraphNode *> copied;
         queue<UndirectedGraphNode *> que;
         
         old2new.insert(pair<UndirectedGraphNode *, UndirectedGraphNode *>(node, new UndirectedGraphNode(node->label)));
         que.push(node);
         while (!que.empty()) {
             UndirectedGraphNode *front = que.front();
             que.pop();
             if (copied.find(front) != copied.end())
                continue;
             for (auto n : front->neighbors) {
                 if (old2new.find(n) == old2new.end()) {
                     UndirectedGraphNode *newNode = new UndirectedGraphNode(n->label);
                     old2new.insert(pair<UndirectedGraphNode *, UndirectedGraphNode *>(n, newNode));
                     que.push(n);
                 }
                 old2new[front]->neighbors.push_back(old2new[n]);
             }
             copied.insert(front);
         }
         
         return old2new[node];
 }