滑动窗口最大值C++代码报错：AddressSanitizer堆缓冲区溢出排查

问题背景 #

给定整数数组nums和大小为k的滑动窗口，窗口从数组最左端移动到最右端，每次右移一位，计算每个窗口内的最大值。输入示例：nums = [1,3,-1,-3,5,3,6,7]，k = 3；预期输出：[3,3,5,5,6,7]。

提供的实现代码运行时触发堆缓冲区溢出错误，报错信息如下：

=================================================================
==31==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x603000000090 at pc 0x000000345e1e bp 0x7ffef610bff0 sp 0x7ffef610bfe8
READ of size 4 at 0x603000000090 thread T0
    #2 0x7fb1bb36d0b2  (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
0x603000000090 is located 0 bytes to the right of 32-byte region [0x603000000070,0x603000000090)
allocated by thread T0 here:
    #6 0x7fb1bb36d0b2  (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
Shadow bytes around the buggy address:
  0x0c067fff7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c067fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c067fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c067fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c067fff8000: fa fa 00 00 00 07 fa fa fd fd fd fa fa fa 00 00
=>0x0c067fff8010: 00 00[fa]fa 00 00 00 00 fa fa fa fa fa fa fa fa
  0x0c067fff8020: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff8030: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff8040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff8050: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff8060: 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
  Shadow gap:              cc
==31==ABORTING

错误原因 #

1. 外层循环范围越界：原代码外层循环for(int i=0; i<n; i++)遍历数组所有元素，但滑动窗口的有效起始位置仅到n-k，超出后窗口会超出数组边界。
2. 内层循环起始索引错误：原代码内层循环从j=1开始，跳过了窗口的第一个元素，同时当i+k超过数组长度时，j会访问数组外的内存，直接触发堆溢出。
3. 后处理逻辑冗余无效：先错误生成过多元素再截断，无法从根源避免越界访问，还降低了代码效率。

修复后的代码 #

class Solution {
public:
    vector<int> maxSlidingWindow(vector<int> &nums, int k) {
        int n = nums.size();
        vector<int> answer;
        // 仅遍历有效窗口的起始位置
        for(int i = 0; i <= n - k; i++){
            int mx = INT_MIN;
            // 遍历当前窗口内的所有元素
            for(int j = i; j < i + k; j++){
                mx = max(mx, nums[j]);
            }
            answer.push_back(mx);
        }
        return answer;
    }
};

修复说明 #

• 调整外层循环条件为i <= n - k，确保每个窗口完全包含在数组范围内，避免越界。
• 内层循环从j=i开始，遍历窗口内的所有元素（i到i+k-1），既不遗漏元素，也不访问数组外内存。
• 移除冗余的后处理截断逻辑，直接生成正确数量的结果元素，提升代码效率。

内容的提问来源于stack exchange，提问作者joy