[数据结构与算法]【leetcode报错】今天你报错了吗20220222

剑指offer 09，30 关于栈遇到的问题

Line 175: Char 16: runtime error: reference binding to misaligned address 0xbebebebebebec0ba for type ‘int’, which requires 4 byte alignment (stl_deque.h)
0xbebebebebebec0ba: note: pointer points here

SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /usr/bin/…/lib/gcc/x86_64-linux-gnu/9/…/…/…/…/include/c++/9/bits/stl_deque.h:180:16

原因分析：

在栈空的时候访问了栈元素就会报错。判断条件错误可能会导致错误访问。

stack<int>stack;
s.top();
s.pop(); 

if判断条件顺序错误，导致可会在栈在空的情况，先判断去访问栈顶元素导致错误。

//错误
if(x <= stack.top() ||stack.empty());
//正确
if(stack.empty() || x <= stack.top());

晚上刷题的时候又遇到类似的问题了！！！对自己无语滴很！！

Line 14: Char 16: runtime error: member access within misaligned address 0x000000000007 for type ‘ListNode’, which requires 8 byte alignment (ListNodeUtils.cpp)
0x000000000007: note: pointer points here

SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ListNodeUtils.cpp:24:16

class Solution {
public:
    ListNode* reverseList(ListNode* head) {
        //我写成了ListNode *pre = head,*cur, *tmp;导致pre->next = cur访问错误
        ListNode *pre = head,*cur = NULL, *tmp = NULL;     
        while(pre != NULL){
            tmp = pre->next;
            pre->next = cur;
            cur = pre;
            pre = tmp;
        }
        return cur;
    }