LeetCode 160. 相交链表

编写一个程序，找到两个单链表相交的起始节点。

如下面的两个链表：

在节点 c1 开始相交。

题解

java代码如下

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode getIntersectionNode(ListNode headA, ListNode headB) {
        int lenA = 0;
        int lenB = 0;
        int gap = 0;
        
        ListNode pA = headA;
        ListNode pB = headB;
        
        while(pA != null) {
            lenA++;
            pA = pA.next;
        }
        
        while(pB != null) {
            lenB++;
            pB = pB.next;
        }
        
        pA = headA;
        pB = headB;
        
        if (lenA < lenB) {
            gap = lenB - lenA;
            while(gap > 0) {
                pB = pB.next;
                gap--;
            }
        } else {
            gap = lenA - lenB;
            while(gap > 0) {
                pA = pA.next;
                gap--;
            }
        }
        
        while(pA != null && pB != null) {
            if(pA == pB) {
                return pA;
            }
            pA = pA.next;
            pB = pB.next;
        }
        
        return null;
    }
}