剑指offer--面试题16

#include<stack>

//思路：遍历链表过程中，将各个指针入栈，再出栈进行反转
ListNode* ReverseList(ListNode* pHead)
{
    if(pHead == NULL)
        return NULL;
    ListNode* pNode = pHead;

    stack<ListNode*> pNodeStack;
    while(pNode != NULL)
    {
        pNodeStack.push(pNode);
        pNode = pNode->m_pNext;
    }

    pNode = pNodeStack.top();
    ListNode* pFront = pNode;
    pNodeStack.pop();

    while(!pNodeStack.empty())
    {
        pNode->m_pNext = pNodeStack.top();
        pNode = pNode->m_pNext;
        pNodeStack.pop();
    }

    pNode->m_pNext = NULL;

    return pFront;
}

不用栈，自己还真不好编。。。

虽然有思路，但写出代码来还比较困难。。。惊叹于作者代码的精炼！！！

学习：

ListNode* ReverseList(ListNode* pHead)
{
    ListNode* pReversedHead = NULL;
    ListNode* pNode = pHead;
    ListNode* pPrev = NULL;
    while(pNode != NULL)
    {
        ListNode* pNext = pNode->m_pNext;

        if(pNext == NULL)
            pReversedHead = pNode;

        pNode->m_pNext = pPrev;

        pPrev = pNode;
        pNode = pNext;
    }

    return pReversedHead;
}