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?微信公眾號：山青詠芝（shanqingyongzhi）
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?原文地址：https://www.cnblogs.com/strengthen/p/9967399.html?
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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.

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給定一個鏈表，每個節點包含一個額外增加的隨機指針，該指針可以指向鏈表中的任何節點或空節點。

要求返回這個鏈表的深度拷貝。?

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1ms

1 /** 2 * Definition for singly-linked list with a random pointer. 3 * class RandomListNode { 4 * int label; 5 * RandomListNode next, random; 6 * RandomListNode(int x) { this.label = x; } 7 * }; 8 */ 9 public class Solution { 10 public RandomListNode copyRandomList(RandomListNode head) { 11 RandomListNode res = new RandomListNode(0); 12 RandomListNode p = res; 13 RandomListNode curr = head; 14 while (curr != null) { 15 p.next = clone(curr); 16 curr = curr.next; 17 p = p.next; 18 } 19 return res.next; 20 } 21 22 private RandomListNode clone(RandomListNode node) { 23 RandomListNode newNode = new RandomListNode(node.label); 24 if (node.random != null) 25 newNode.random = new RandomListNode(node.random.label); 26 return newNode; 27 } 28 }

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2ms

1 /** 2 * Definition for singly-linked list with a random pointer. 3 * class RandomListNode { 4 * int label; 5 * RandomListNode next, random; 6 * RandomListNode(int x) { this.label = x; } 7 * }; 8 */ 9 public class Solution { 10 public RandomListNode copyRandomList(RandomListNode head) { 11 if(head == null) return head; 12 copyNext(head); 13 copyRandom(head); 14 15 RandomListNode curr = head; 16 RandomListNode newHead = head.next; 17 RandomListNode start = newHead; 18 while(curr!=null && curr.next!=null){ 19 RandomListNode next = curr.next.next; 20 curr.next = next; 21 curr = next; 22 23 if(start.next!=null) { 24 start.next = start.next.next; 25 start = start.next; 26 } 27 } 28 29 return newHead; 30 } 31 32 private void copyNext(RandomListNode head){ 33 if(head == null) return; 34 35 RandomListNode curr = head; 36 while(curr!=null){ 37 RandomListNode next = curr.next; 38 curr.next = new RandomListNode(curr.label); 39 curr.next.random = curr.random; 40 curr.next.next = next; 41 curr = next; 42 } 43 } 44 45 private void copyRandom(RandomListNode head) { 46 if(head == null) return; 47 RandomListNode curr = head; 48 while(curr!=null && curr.next!=null){ 49 RandomListNode next = curr.next.next; 50 if(curr.next!=null && curr.random!=null){ 51 curr.next.random = curr.random.next; 52 } 53 curr = next; 54 } 55 } 56 }

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2ms

1 /** 2 * Definition for singly-linked list with a random pointer. 3 * class RandomListNode { 4 * int label; 5 * RandomListNode next, random; 6 * RandomListNode(int x) { this.label = x; } 7 * }; 8 */ 9 public class Solution { 10 public RandomListNode copyRandomList(RandomListNode head) 11 { 12 RandomListNode root = null, prev = null, rootIter = head; 13 14 while (rootIter != null) 15 { 16 RandomListNode newCopy = new RandomListNode(rootIter.label); 17 newCopy.next = null; 18 newCopy.random = null; 19 20 prev = rootIter; 21 rootIter = rootIter.next; 22 23 prev.next = newCopy; 24 newCopy.next = rootIter; 25 /* 'prev' points to previous rootIter whose 'next' will point 26 to the new copy of previous rootIter created in 'newCopy' */ 27 } 28 if (head == null) 29 root = null; 30 31 else 32 root = head.next; 33 34 rootIter = head; 35 while (rootIter != null) 36 { 37 if (rootIter.random == null) 38 rootIter.next.random = null; 39 40 else 41 rootIter.next.random = rootIter.random.next; 42 43 rootIter = rootIter.next.next; 44 } 45 46 rootIter = head; 47 while (rootIter != null) 48 { 49 RandomListNode nextNode = rootIter.next.next; 50 if (nextNode != null) 51 rootIter.next.next = nextNode.next; 52 53 rootIter.next = nextNode; 54 rootIter = nextNode; 55 } 56 return root; 57 } 58 }

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3ms

1 /** 2 * Definition for singly-linked list with a random pointer. 3 * class RandomListNode { 4 * int label; 5 * RandomListNode next, random; 6 * RandomListNode(int x) { this.label = x; } 7 * }; 8 */ 9 public class Solution { 10 11 private Map<RandomListNode,RandomListNode> visited = new HashMap<>(); 12 13 public RandomListNode copyRandomList(RandomListNode head) { 14 if(head == null){ 15 return null; 16 } 17 18 if(visited.containsKey(head)){ 19 return visited.get(head); 20 } 21 22 RandomListNode newNode = new RandomListNode(head.label); 23 visited.put(head,newNode); //at this point in time, we have newed this node. does not matter if we need to recurse further to have it fully constructed. this is already copied. thus mark it as visited 24 25 newNode.next = copyRandomList(head.next); 26 newNode.random = copyRandomList(head.random); 27 28 29 return newNode; 30 31 } 32 }

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轉載于:https://www.cnblogs.com/strengthen/p/9967399.html

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