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];
  }