标签：des style blog color io ar 使用 java for
Clone Graph:
Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.
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 #.
0. Connect node 0 to both nodes 1 and 2.1. Connect node 1 to node 2.2. Connect node 2 to node 2 (itself), thus forming a self-cycle.
Visually, the graph looks like the following:
1
/ / 0 --- 2
/ \_/
对于图的遍历，无非是深度优先和广度优先。在这里采用的是广度优先搜索。
题目的关键点在于完全克隆，也就是说遇到的每一个节点必须复制一份出来，另外如果有连通的边（指针），也需要复制一份出来。
采用HashMap将原节点与克隆节点进行对应可以实现。在遍历到节点X时，也得到X‘,对X的所有相邻节点进行讨论，如果是新相邻节点（HashMap中不存在）N，则复制一份N‘，复制点N‘与X‘相连，并把对应的二者（N,N‘）放入HashMap中，新相邻节点（N）入队列。
如果发现节点N已遍历过，则只需要把它复制点N‘与当前遍历点的复制点X‘连接，即为复制一条边。
代码：
1 public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) { 2 if(node==null) 3 return null; 4 Queue<UndirectedGraphNode> q = new LinkedList<UndirectedGraphNode>(); 5 HashMap<UndirectedGraphNode, UndirectedGraphNode> hm = new HashMap<UndirectedGraphNode, UndirectedGraphNode>(); 6 7 q.add(node); 8 UndirectedGraphNode copy = new UndirectedGraphNode(node.label); 9 hm.put(node, copy); 10 while(!q.isEmpty()) 11 { 12 UndirectedGraphNode temp = q.poll(); 13 UndirectedGraphNode tempCopy = hm.get(temp); 14 List<UndirectedGraphNode> N = temp.neighbors; 15 for(int i=0;i<N.size();i++) { 16 UndirectedGraphNode tempN = N.get(i); 17 if(!hm.containsKey(tempN)) { 18 UndirectedGraphNode copyN = new UndirectedGraphNode(tempN.label); 19 tempCopy.neighbors.add(copyN); 20 hm.put(tempN, copyN); 21 q.add(tempN); 22 } 23 else { 24 tempCopy.neighbors.add(hm.get(tempN)); 25 } 26 } 27 } 28 return copy; 29 }
Copy List with Random Pointer:
A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null.
Return a deep copy of the list.
这题感觉像是Clone Graph的简化版（相邻节点个数最多为2个），不知道是不是理解有误，总之使用以上的思路是可以通过的。唯一区别是要讨论节点为空的情况，只有不为空的相邻节点才需要讨论。
代码：
1 public RandomListNode copyRandomList(RandomListNode head) { 2 if(head==null) 3 return null; 4 Queue<RandomListNode> q = new LinkedList<RandomListNode>(); 5 q.add(head); 6 HashMap<RandomListNode,RandomListNode> hm = new HashMap<RandomListNode,RandomListNode>(); 7 RandomListNode headCopy = new RandomListNode(head.label); 8 hm.put(head,headCopy); 9 while(!q.isEmpty()) 10 { 11 RandomListNode temp = q.poll(); 12 RandomListNode copyTemp = hm.get(temp); 13 RandomListNode nTemp = temp.next; 14 RandomListNode rTemp = temp.random; 15 if(nTemp!=null) 16 { 17 if(!hm.containsKey(nTemp)) { 18 RandomListNode copyNext = new RandomListNode(nTemp.label); 19 copyTemp.next = copyNext; 20 hm.put(nTemp,copyNext); 21 q.add(nTemp); 22 } 23 else 24 copyTemp.next = hm.get(nTemp); 25 } 26 if(rTemp!=null) 27 { 28 if(!hm.containsKey(rTemp)) { 29 RandomListNode copyRandom = new RandomListNode(rTemp.label); 30 copyTemp.random = copyRandom; 31 hm.put(rTemp,copyRandom); 32 q.add(rTemp); 33 } 34 else 35 copyTemp.random = hm.get(rTemp); 36 } 37 } 38 return headCopy; 39 }
[Leetcode][JAVA] Clone Graph, Copy List with Random Pointer
标签：des style blog color io ar 使用 java for
原文地址：http://www.cnblogs.com/splash/p/4047336.html
