Clone Graph [leetcode] dfs和bfs

变量unordered_map<UndirectedGraphNode *, UndirectedGraphNode *> cloneMap;

因为会有环，所以需要cloneMap记录旧的节点和新的节点对。

还需要一个visited记录已经访问过的节点，可以和cloneMap合并在一起。

DFS：

在克隆某个Node时，首先放入map中。

之后遍历neighbors。如果neighbors不在map里，即没有访问过，则递归调用cloneGraph函数。

最后返回克隆过的节点。

UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
if (node == NULL) return NULL;
if (cloneMap.find(node) != cloneMap.end())
return cloneMap[node];
cloneMap[node] = new UndirectedGraphNode(node->label);
cloneMap[node]->neighbors = vector<UndirectedGraphNode *>();
for (int i = 0; i < node->neighbors.size(); i++)
{
UndirectedGraphNode * curNode = node->neighbors[i];
UndirectedGraphNode * newNode = cloneGraph(curNode);
cloneMap[node]->neighbors.push_back(newNode);
}
return cloneMap[node];
}

BFS：

使用一个queue记录要访问的节点。

因为不能在访问queue中节点的时候再创建对应的node==>因为在处理父亲节点的时候需同时创建好其neighbors

所以需要在将不在map中的neighbors（没有访问过的子节点）放入queue的同时创建克隆的节点，并且放入map里。

UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
if (node == NULL) return NULL;
vector<UndirectedGraphNode *> queue;
queue.push_back(node);
cloneMap[node] = new UndirectedGraphNode(node->label);
cloneMap[node]->neighbors = vector<UndirectedGraphNode *>();

for (int i = 0; i < queue.size(); i++)
{
UndirectedGraphNode * newNode = cloneMap[queue[i]];
for (int j = 0; j < queue[i]->neighbors.size(); j++)
{
UndirectedGraphNode * curNb = queue[i]->neighbors[j];
if (cloneMap.find(curNb) == cloneMap.end())
{
queue.push_back(curNb);
UndirectedGraphNode * newNb = new UndirectedGraphNode(curNb->label);
newNb->neighbors = vector<UndirectedGraphNode *>();
cloneMap[curNb] = newNb;
}
newNode->neighbors.push_back(cloneMap[curNb]);
}
}
return cloneMap[node];
}