数据结构练习（26）在字符串中删除特定的字符

http://zhedahht.blog.163.com/blog/static/25411174200801931426484/

思路：

关于删除字符处理的特别巧妙，双指针移动的方法，最终时间复杂度为O(n).

需要注意的一点是：最后不能忘记给src字符串加上'\0'

#include <iostream>
#include <cstring>
using namespace std;

void DeleteChars(char *src, const char *dst)
{
    if (!src || !dst)
        return;

    const int hashsize = 256;
    int hash[hashsize];
    memset(hash, 0, sizeof(hash));

    const char *p = dst;
    while (*p != '\0')
    {
        hash[*p] = 1;
        ++p;
    }

    char *pfast = src;
    char *pslow = src;

    while (*pfast != '\0')
    {
        if (hash[*pfast] != 1)
        {
            *pslow = *pfast;
            ++pslow;
        }
        ++pfast;
    }
    *pslow = '\0';
}

int main()
{
    char s1[100] = "They are students.";
    char s2[100] = "aeiou";
    DeleteChars(s1, s2);
    return 0;
}