问题描述
输入一个链表,反转链表后,输出新链表的表头。
c++代码
/*
struct ListNode {
int val;
struct ListNode *next;
ListNode(int x) :
val(x), next(NULL) {
}
};*/
class Solution {
public:
ListNode* ReverseList(ListNode* pHead) {
if(pHead == NULL) return pHead;
ListNode *cur = pHead, *nxt, *pre = NULL;
while(cur != NULL){
nxt = cur->next;
cur->next = pre;
pre = cur;
cur = nxt;
}
return pre;
}
};
python代码
# -*- coding:utf-8 -*-
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
class Solution:
# 返回ListNode
def ReverseList(self, pHead):
# write code here
if not pHead:
return pHead
cur, pre = pHead, None
while cur:
nxt = cur.next
cur.next = pre
pre = cur
cur = nxt
return pre