題目描述
輸入一個複雜鏈表(每個節點中有節點值,以及兩個指針,一個指向下一個節點,另一個特殊指針random指向一個隨機節點),請對此鏈表進行深拷貝,並返回拷貝後的頭結點。(注意,輸出結果中請不要返回參數中的節點引用,否則判題程序會直接返回空)
第二種思路
package linkedList;
import java.util.HashMap;
/*
複雜鏈表的複製
題目描述
輸入一個複雜鏈表(每個節點中有節點值,以及兩個指針,一個指向下一個節點,
另一個特殊指針random指向一個隨機節點),請對此鏈表進行深拷貝,並返回拷貝後的頭結點。
(注意,輸出結果中請不要返回參數中的節點引用,否則判題程序會直接返回空)
*/
public class Clone_25 {
public RandomListNode clone(RandomListNode pHead) {
HashMap<RandomListNode, RandomListNode> map = new HashMap<RandomListNode, RandomListNode>();
RandomListNode p = pHead;
//第一次遍歷 將複雜鏈表存入map,key:鏈表節點,value:節點對應的值
while(p != null){
RandomListNode newNode = new RandomListNode(p.label);
map.put(p, newNode);
p = p.next;
}
//第二次遍歷 深拷貝鏈表,並賦值指針random的映射關係
p = pHead;
while(p != null){
RandomListNode node = map.get(p);
node.next = (p.next == null)?null: map.get(p.next);
node.random = (p.random == null)?null: map.get(p.random);
p = p.next;
}
//最後的返回值,返回拷貝後的頭結點
return map.get(pHead);
}
/*
*第二種解題思路:
*1、遍歷鏈表,複製每個結點,如複製結點A得到A1,將結點A1插到結點A後面;
*2、重新遍歷鏈表,複製老結點的隨機指針給新結點,如A1.random = A.random.next;
*3、拆分鏈表,將鏈表拆分爲原鏈表和複製後的鏈表
*/
public RandomListNode clone1(RandomListNode pHead) {
if(pHead == null) {
return null;
}
RandomListNode currentNode = pHead;
//1、複製每個結點,如複製結點A得到A1,將結點A1插到結點A後面;
while(currentNode != null){
RandomListNode cloneNode = new RandomListNode(currentNode.label);
RandomListNode nextNode = currentNode.next;
currentNode.next = cloneNode;
cloneNode.next = nextNode;
currentNode = nextNode;
}
currentNode = pHead;
//2、重新遍歷鏈表,複製老結點的隨機指針給新結點,如A1.random = A.random.next;
while(currentNode != null) {
currentNode.next.random = currentNode.random==null?null:currentNode.random.next;
currentNode = currentNode.next.next;
}
//3、拆分鏈表,將鏈表拆分爲原鏈表和複製後的鏈表
currentNode = pHead;
RandomListNode pCloneHead = pHead.next;
while(currentNode != null) {
RandomListNode cloneNode = currentNode.next;
currentNode.next = cloneNode.next;
cloneNode.next = cloneNode.next==null?null:cloneNode.next.next;
currentNode = currentNode.next;
}
return pCloneHead;
}
public static void main(String[] args) {
Clone_25 clone_25 = new Clone_25();
RandomListNode pHead = new RandomListNode(1);
pHead.next = new RandomListNode(2);
pHead.next.next = new RandomListNode(3);
pHead.next.next.next = new RandomListNode(4);
pHead.next.next.next.next = new RandomListNode(5);
pHead.random = new RandomListNode(3);
pHead.next.random = new RandomListNode(5);
pHead.next.next.next.next.random = new RandomListNode(2);
RandomListNode head = clone_25.clone(pHead);
System.out.println(head.label);
}
}