LeetCode 面试题 02.07. 链表相交

/**

• Definition for singly-linked list.

• struct ListNode {

• int val;
  

• ListNode *next;
  

• ListNode(int x) : val(x), next(NULL) {}
  

• };
  */
  class Solution {
  public:
  ListNode *move(ListNode *head, int n) {
  while (n --) {
  head = head ->next;
  }

   return head;
  

  }

  ListNode *getIntersectionNode(ListNode headA, ListNode headB) {
  ListNode A = headA;
  ListNode B = headB;
  int length_A = 0, length_B = 0;
  while (A) A = A ->next, length_A ++;
  while (B) B = B ->next, length_B ++;

   if (length_A >= length_B) {
       int n = length_A - length_B;
       while (n --) {
       headA = headA ->next;
       }
   } 
   else {
       int n = length_B - length_A;
       while (n --) {
       headB = headB ->next;
       } 
   }
  
   while (headA) {
       if (headA == headB) return headA ;
  
       headA = headA ->next;
       headB = headB ->next;
   }
  
   return NULL;
  

  }
  };