最近博主看网上有人说一定要把leetcode前几百道刷一遍,于是决定刷刷消遣一下,没想到第一道题就出了问题,感觉想对算法和跑通算法之间还是隔了很远,于是将所有刷题时遇到的问题汇总到这里。
⚠️此篇文章是以问题为单位写的,所以完整代码我不会贴在这里,我在leetcode的用户名和CSDN用户名是一样的,那里我按题为单位写了题解,读者可以去那里看完整代码。
一、不要忽视题目给定的任何参数
报错信息
=================================================================
==29==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x602000000038 at pc 0x000000405105 bp 0x7ffda29df000 sp 0x7ffda29deff8
READ of size 4 at 0x602000000038 thread T0
#2 0x7f660e1e82e0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202e0)
0x602000000038 is located 0 bytes to the right of 8-byte region [0x602000000030,0x602000000038)
allocated by thread T0 here:
#0 0x7f660fa972b0 in malloc (/usr/local/lib64/libasan.so.5+0xe82b0)
#3 0x7f660e1e82e0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202e0)
Shadow bytes around the buggy address:
0x0c047fff7fb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c047fff7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c047fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c047fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c047fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c047fff8000: fa fa 00 00 fa fa 00[fa]fa fa fd fa fa fa fd fa
0x0c047fff8010: fa fa fd fa fa fa 00 fa fa fa fa fa fa fa fa fa
0x0c047fff8020: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8030: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8050: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
==29==ABORTING
题目、原因和解决方法
【leetcode第一题】要求从给定数组中找出相加为给定数字的两个数,用一个长度为2的数组存放这两个数的数组下标。题目给定的模板为:
int* twoSum(int* nums, int numsSize, int target, int* returnSize){
,其中returnSize是为了让你指定存放结果的数组的长度,虽然题目没有告之这一点,但要记得加一句:
*returnSize = 2;
不然会报溢出的错误。
经验小结
不要忽略题目给的参数,要认真思考每个参数的意义。
二、将结点链接到链表末尾
题目简述和错误信息
【leetcode第二题】用两个单链表分别逆序存储两个整数,一个结点中放一位。计算结果也逆序放在单链表中。
出现的错误是:输出的结果是一个空的单链表。
错误原因和解决方法
改正之后的代码中有很多处都出现了这两行:
cur->next = (struct ListNode*)malloc(sizeof(struct ListNode));
cur=cur->next;
改正之前,这两行写反了…
可以想想写反了会怎么样:cur
先指向cur->next
指向的位置(为NULL
),这个操作仅仅将cur
赋值为NULL
,起不到让结点的前驱指向它自己的作用。