125.md

#125. Valid Palindrome 题目链接

int isAlphanumeric(char c)
{
    if ((c>='a'&&c<='z') || (c>='A'&&c<='Z') || c>='0'&&c<='9')
        return 1;
    return 0;
}

char toLowerCase(char c)
{
    if (c>='A' && c<='Z')
        return c - ('A' - 'a');
    return c;
}

int isPalindrome(char *s)
{
    int start=0,end = 0;
    while(s[end] != '\0')
    {
        end++;
    }
    while(start != end && start-1 != end)
    {
        if(!isAlphanumeric(s[start]))
        {
            start++;
            continue;
        }
        if(!isAlphanumeric(s[end]))
        {
            end--;
            continue;
        }
        if(toLowerCase(s[start]) != toLowerCase(s[end]))
        {
            return 0;
        }
        start++;end--;
    }
    return 1;
}