public static RandomListNode CopyRandomList(RandomListNode head)
{
if (head == null)
{
return(null);
}
var cur = head;
var nodeMap = new Dictionary <RandomListNode, RandomListNode>();
while (cur != null)
{
nodeMap.Add(cur, new RandomListNode(cur.label));
cur = cur.next;
}
cur = head;
while (cur != null)
{
nodeMap[cur].next = nodeMap[cur.next];
nodeMap[cur].random = nodeMap[cur.random];
cur = cur.next;
}
return(nodeMap[head]);
}
/// <summary>
/// 通过数组构建带随机指针的链表
/// </summary>
/// <param name="vals"></param>
/// <returns></returns>
private static RandomListNode CreateRandomListNodes(int[] vals)
{
var dummy = new RandomListNode(0);
var nodeList = new List <RandomListNode>();
var curr = dummy;
for (int i = 0; i < vals.Length; i++)
{
curr.next = new RandomListNode(vals[i]);
nodeList.Add(curr.next);
curr = curr.next;
}
nodeList.Add(null);
curr = dummy;
var random = new Random();
while (curr.next != null)
{
var rdm = random.Next(0, nodeList.Count);
curr.next.random = nodeList.ElementAt(rdm);
curr = curr.next;
}
return(dummy.next);
}
public RandomListNode CopyRandomList(RandomListNode head)
{
if (head == null)
{
return(null);
}
//In place copy
CopyNext(head);
CopyRandomNode(head);
return(ExtractCopiedNode(head));
}
/// <summary>
/// 带随机指针的链表打印
/// </summary>
/// <param name="node"></param>
private static void PrintRandomListNode(RandomListNode node)
{
RandomListNode curr = node;
var outVals = new List <string>();
while (curr != null)
{
var randomLable = curr.random == null ? "NULL" : curr.random.label.ToString();
outVals.Add(curr.label + "[" + randomLable + "]");
curr = curr.next;
}
Console.WriteLine(string.Join(" -> ", outVals));
}
private void CopyNext(RandomListNode head)
{
while (head != null)
{
var copyNode = new RandomListNode(head.label)
{
next = head.next,
random = head.random
};
head.next = copyNode;
head = head.next.next;
}
}
public static string PrintListNode(RandomListNode head)
{
string result = string.Empty;
while (head != null)
{
var randomStr = head.random != null?head.random.val.ToString() : "";
result = result + head.val.ToString() + "_" + randomStr + "=>";
head = head.next;
}
return(result);
}
private void CopyRandomNode(RandomListNode head)
{
while (head != null)
{
if (head.next.random != null)
{
// OriginalNode.random.next is the copy of OriginalNode.random
// Replace Copied node.random with the copy
head.next.random = head.random.next;
}
head = head.next.next;
}
}
public RandomListNode CopyRandomList(RandomListNode head)
{
RandomListNode iter = head, next;
// 第1步: 遍历原链表，拷贝每个节点，并将拷贝后的节点插入原先节点之后
while (iter != null)
{
next = iter.next;
RandomListNode copyNode = new RandomListNode(iter.label);
iter.next = copyNode;
copyNode.next = next;
iter = next;
}
// 第2步: 遍历新链表，将随机节点指针赋值给拷贝后的节点
iter = head;
while (iter != null)
{
if (iter.random != null)
{
iter.next.random = iter.random.next;
}
iter = iter.next.next;
}
// 第3步: 复原原链表，并构造新的深拷贝链表
iter = head;
RandomListNode pseudoHead = new RandomListNode(0);
RandomListNode copy, copyIter = pseudoHead;
while (iter != null)
{
next = iter.next.next;
copy = iter.next;
copyIter.next = copy;
copyIter = copy;
iter.next = next;
iter = next;
}
return(pseudoHead.next);
}
private RandomListNode ExtractCopiedNode(RandomListNode head)
{
RandomListNode r = head.next;
while (head != null)
{
// 1 -> Copy 1 -> 2 -> Copy 2
var temp = head.next;
head.next = temp.next;
head = head.next;
if (temp.next != null)
{
temp.next = temp.next.next;
}
}
return(r);
}
public RandomListNode CopyRandomList(RandomListNode head)
{
if (null == head)
{
return(null);
}
var dic = new Dictionary <RandomListNode, RandomListNode>();
var createdNode = new RandomListNode(head.label);
var useQueue = new Queue <RandomListNode>();
useQueue.Enqueue(head);
dic.Add(head, createdNode);
while (useQueue.Count != 0)
{
var node = useQueue.Dequeue();
var dicNode = dic[node];
if (null != node.next)
{
useQueue.Enqueue(node.next);
if (!dic.ContainsKey(node.next))
{
dic.Add(node.next, new RandomListNode(node.next.label));
}
dicNode.next = dic[node.next];
}
if (null != node.random)
{
if (!dic.ContainsKey(node.random))
{
dic.Add(node.random, new RandomListNode(node.random.label));
}
dicNode.random = dic[node.random];
}
}
return(dic[head]);
}
private RandomListNode GetOrAddRandomList(Dictionary <RandomListNode, RandomListNode> dic, RandomListNode node)
{
if (node == null)
{
return(null);
}
if (dic.ContainsKey(node))
{
return(dic[node]);
}
else
{
var newNode = new RandomListNode(node.label);
dic.Add(node, newNode);
newNode.next = GetOrAddRandomList(dic, node.next);
newNode.random = GetOrAddRandomList(dic, node.random);
return(newNode);
}
}
// 已知一个复杂的链表，节点中有一个指向本链表任意某个节点的随机指针（可以为null），实现这个链表的深度拷贝
public static RandomListNode DeepCloneRandomListNode(RandomListNode head)
{
RandomListNode tempNode = null;
var nodeToIDMap = new Dictionary <RandomListNode, int>();
int id = 0;
tempNode = head;
while (tempNode != null)
{
if (!nodeToIDMap.ContainsKey(tempNode))
{
nodeToIDMap.Add(tempNode, id);
id++;
}
tempNode = tempNode.next;
}
var idToNodeMap = new Dictionary <int, RandomListNode>();
id = 0;
RandomListNode newHead = null;
RandomListNode newNode = null;
RandomListNode tempHeadNode = head;
while (tempHeadNode != null)
{
tempNode = new RandomListNode(tempHeadNode.val, null, null);
if (newHead == null)
{
newHead = tempNode;
}
else
{
newNode.next = tempNode;
}
newNode = tempNode;
if (!idToNodeMap.ContainsKey(id))
{
idToNodeMap.Add(id, tempNode);
id++;
}
tempHeadNode = tempHeadNode.next;
}
tempNode = newHead;
while (tempNode != null && head != null)
{
if (head.random == null)
{
tempNode.random = null;
}
else
{
var currentId = nodeToIDMap[head.random];
tempNode.random = idToNodeMap[currentId];
}
head = head.next;
tempNode = tempNode.next;
}
return(newHead);
}
public RandomListNode(int val, RandomListNode next, RandomListNode random)
{
this.val = val;
this.next = next;
this.random = random;
}
public RandomListNode CopyRandomList(RandomListNode head)
{
var dic = new Dictionary <RandomListNode, RandomListNode>();
return(GetOrAddRandomList(dic, head));
}