码农小汪-剑指Offer之34 -两个链表的第一个公共结点 hashMap

题目描述

解题思路如下：

package JianzhiOffer;

import java.util.HashMap;
import java.util.Map;

class ListNode {
int val;
ListNode next = null;

ListNode(int val) {
this.val = val;
}
}

public class Slution34 {
/**
* 利用Map做
*
* @param pHead1
* @param pHead2
* @return
*/
public ListNode FindFirstCommonNode(ListNode pHead1, ListNode pHead2) {
if (pHead1 == null || pHead2 == null) {
return null;
}
Map<ListNode, Integer> map = new HashMap<ListNode, Integer>();
while (pHead1 != null) {
map.put(pHead1, pHead1.val);
pHead1 = pHead1.next;
}
while (pHead2 != null) {
if (map.containsValue(pHead2.val)) {
return pHead2;
}
pHead2 = pHead2.next;
}
return null;
}
}