Question

我正在尝试提交有关leetcode的解决方案，当我提交它时，这会给我一个运行时错误。

AddressSanitizer: stack-buffer-overflow on address 0x7ffd6484f411 at pc 0x000000386795 bp 0x7ffd6484ed70 sp 0x7ffd6484ed68

这是我的代码：

int lengthOfLongestSubstring(std::string s)
{
    auto start = std::begin(s);
    std::string substring = std::string(std::begin(s), std::begin(s) + 1);
    std::string pre_string = std::string(std::begin(s), std::begin(s) + 1);
    for (auto itr = std::begin(s) + 1; itr != std::end(s); ++itr)
    {
        auto next = itr;
        if (std::find(std::begin(substring), std::end(substring), *itr) ==
            std::end(substring))
        {
            substring = std::string(start, itr + 1);
        }
        else
        {
            if (++next != std::end(s))
            {
                start = itr;
                pre_string = substring;
                substring = std::string(itr, ++itr);
            }
        }
    }

    if (pre_string.length() > substring.length())
    {
        return pre_string.length();
    }
    else
        return substring.length();
}

当我尝试在计算机上运行它时，它不会给我任何警告。运行完全正常。我正在使用以下命令。 g++ -Wall -Wpedantic longestString.cpp -o long.o

然后我使用valgrind来查看任何问题，但它也表示没有问题，因为您可以看到输出。

username@droozal:~/leetcode$ valgrind ./long.o
==9473== Memcheck, a memory error detector
==9473== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==9473== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==9473== Command: ./long.o
==9473== 
5
==9473== 
==9473== HEAP SUMMARY:
==9473==     in use at exit: 0 bytes in 0 blocks
==9473==   total heap usage: 2 allocs, 2 frees, 73,728 bytes allocated
==9473== 
==9473== All heap blocks were freed -- no leaks are possible
==9473== 
==9473== For counts of detected and suppressed errors, rerun with: -v
==9473== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

所以我的问题是潜在的错误是什么？我的代码有问题吗？还是什么？答案将不胜感激。谢谢。

Answer 1

我想，我看到您正在尝试用恒定的内存来解决。您可以使用备忘录，但是对于此问题，代码/调试要简单得多。

这将通过：

#include <string>
#include <map>
#include <algorithm>

class Solution {
public:
    static inline int lengthOfLongestSubstring(const std::string s) {
        map<char, int> char_map;
        int start = -1;
        int longest = 0;
        const int length = s.size();
        for (int index = 0; index < length; index++) {
            if (char_map.count(s[index]) != 0) {
                start = std::max(start, char_map[s[index]]);
            }

            char_map[s[index]] = index;
            longest = std::max(longest, index - start);

        }

        return longest;
    }
};

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在Leetcode上提交解决方案时出现堆栈缓冲区溢出错误

1 个答案:

参考文献