Clone Graph

curNodeClone.neighbors.add(curNodeNeighborClone);

/**
* @param node: A undirected graph node
* @return: A undirected graph node
*/
public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
if (node == null) {
return null;
}
// 放原始node和其复制品
Map<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<>();
// BFS用的queue
List<UndirectedGraphNode> list = new LinkedList<UndirectedGraphNode>();
// 根节点的复制
UndirectedGraphNode nodeClone = new UndirectedGraphNode(node.label);
// 把根节点和其复制品放入map
map.put(node, nodeClone);
//添加入队列
list.add(node);
while (!list.isEmpty()) {
// 当前处理对象
UndirectedGraphNode curNode = list.remove(0);
// 得到当前原始对象的所有neighbor
ArrayList<UndirectedGraphNode> curNodeNeighbors = curNode.neighbors;
// 当前处理对象的复制品，必定在map里，因为在前面的neighbor里已经被创建
UndirectedGraphNode curNodeClone = map.get(curNode);
for (UndirectedGraphNode curNodeNeighbor: curNodeNeighbors) {
if (map.containsKey(curNodeNeighbor)) {
//UndirectedGraphNode curNodeClone = map.get(curNode);
// 之前已经被复制过的neighbor
UndirectedGraphNode curNodeNeighborClone = map.get(curNodeNeighbor);
// 就直接从map里取出neighborClone, 给curClone添加复制的neighbor
curNodeClone.neighbors.add(curNodeNeighborClone);
} else {
// 如果该neighbor没有被复制过，则新建neighborClone
UndirectedGraphNode curNodeNeighborClone = new UndirectedGraphNode(curNodeNeighbor.label);
//UndirectedGraphNode curNodeClone = map.get(curNode);
curNodeClone.neighbors.add(curNodeNeighborClone);
// 并且添加到队列里为了将来的遍历
list.add(curNodeNeighbor);
// 存储到map里
map.put(curNodeNeighbor, curNodeNeighborClone);
}
}
}
return nodeClone;
}