四种语言刷算法之相交链表

力扣160. 相交链表

1、C

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */
struct ListNode *getIntersectionNode(struct ListNode *headA, struct ListNode *headB) {
   if(headA==NULL||headB==NULL)return NULL;
   struct ListNode* p = headA;
   struct ListNode* q = headB;
   while(p!=q){
       if(p!=NULL){
           p = p->next;
       }
       else{
           p = headB;
       }
       if(q!=NULL){
           q = q->next;
       }
       else{
           q = headA;
       }
   } 
   return q;
}

2、C++

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *getIntersectionNode(ListNode *headA, ListNode *headB) {
        if(!headA||!headB)return NULL;
        ListNode *p = headA;
        ListNode *q = headB;
        while(p!=q){
            if (p) p = p->next;
            else p = headB;
            if(q) q = q->next;
            else q = headA;
        }
        return p;
    }
};

3、JAVA

/**
 * 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) {
        if(headA==null||headB==null)return null;
        ListNode p = headA;
        ListNode q = headB;
        while(p!=q){
            if(p!=null) p = p.next;
            else p = headB;
            if(q!=null) q = q.next;
            else q = headA;
        }
        return p;
    }
}

4、Python

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None
class Solution(object):
    def getIntersectionNode(self, headA, headB):
        """
        :type head1, head1: ListNode
        :rtype: ListNode
        """
        if headA is None or headB is None:return None
        p = headA
        q = headB
        while p!=q:
            if p is None:
                p = headB
            else:
                p = p.next
            if q is None:
                q = headA
            else:
                q = q.next
        return p