LeetCode

Reverse Linked List

2015.5.6 05:04

Reverse a singly linked list.

Solution:

　　Too old.

Accepted code:

// 1CE, 1AC, not perfect
/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* reverseList(ListNode* head) {
        if (head == NULL) {
            return NULL;
        }
        
        ListNode *p1 = head;
        ListNode *p2 = p1->next;
        p1->next = NULL;
        ListNode *p3;
        while (p2 != NULL) {
            p3 = p2->next;
            p2->next = p1;
            p1 = p2;
            p2 = p3;
        }
        return p1;
    }
};