字符串、数组相关经典编程题面试题-优快云博客

本文介绍了使用C语言实现的三种字符串操作：判断字符串中是否存在重复字符、逆转C风格字符串以及移除字符串中的重复字符，且在不使用额外数据结构的情况下完成。

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Implement an algorithm to determine if a string has all unique characters What if you can not use additional data structures?

如何判断字符串中是否有重复的字符？

bool isUniqueChar(string s)
{
    bool h[256]={0};
    for (int i=0; i<=s.size()-1; ++i)
    {
        if (h[s[i]]) return false;
        h[s[i]] = 1;
    }
    return true;
}

如何将C的字符数组（char *）逆转？

Write code to reverse a C-Style String (C-String means that “abcd” is represented as five characters, including the null character )

void cStringReverse(char *s)
{
    char *end = s;
    char tmp;
    if (s)
    {
        while (*end) ++end;
        --end;
        while (s < end)
        {
            *s++ = *end--;
        }

    }
}

如何将字符数组重复的字符去除？不允许使用额外的存储空间。

Design an algorithm and write code to remove the duplicate characters in a string without using any additional buffer. NOTE: One or two additional variables are fine. An extra copy of the array is not.

void removeDuplicateChar(char *s)
{
    char *end = s+1;
    char *p = s+1;
    if (s)
    {
        while (*p)
        {
            char *q = s;
            while (q < p)
            {
                if (*p == *q)
                {
                    break;
                }
                ++q;
            }
            if (p == q)
            {
                *end = *p;
                ++end;
            }
            ++p;
        }
        *end = '\0';
    }
}