LeetCode160.相交链表【最通俗易懂版双指针】

160. 相交链表 - 力扣（LeetCode）

/*** Definition for singly-linked list.* public class ListNode {*     int val;*     ListNode next;*     ListNode(int x) {*         val = x;*         next = null;*     }* }*/
public class Solution {/**设 相交节点为 O，尾节点为 C，len(A->O) = a，len(B->O) = b，len(O->C) = c则1. len(A->C) = a + c2. len(B->C) = b + c1式和2式作差得 |a-b| = |lenA - lenB|故 让长链表先走|a-b|步后，再以步长1遍历，A与B将在O相遇*/public ListNode getIntersectionNode(ListNode headA, ListNode headB) {int lenA = 0, lenB = 0;ListNode pA = headA, pB = headB;while (pA != null) {lenA ++;pA = pA.next;}while (pB != null) {lenB ++;pB = pB.next;}if (lenB > lenA) {for (int i = 0; i < lenB - lenA; i ++) {headB = headB.next;}} else {for (int i = 0; i < lenA - lenB; i ++) {headA = headA.next;}}while (headA != null && headB != null) {if (headA == headB) {return headA;}headA = headA.next;headB = headB.next;}return null;}
}