code fighter - interview - str1

You have been given a string s, which is supposed to be a sentence. However, someone forgot to put spaces between the different words, and for some reason they capitalized the first letter of every word. Return the sentence after making the following amendments:

• Put a single space between the words.
• Convert the uppercase letters to lowercase.

Example

• For s = "CodefightsIsAwesome", the output should be
  amendTheSentence(s) = "codefights is awesome";
• For s = "Hello", the output should be
  amendTheSentence(s) = "hello".

char * amendTheSentence(char * s) {

    char buffer[strlen(s)*2];
    int i=0;
    
    char *ptr = s;
    if(*s < 'a')
        buffer[i++] = *s++ - 'A' + 'a';
    else
        buffer[i++] = *s++;
    
    while(*s)
    {
        if(*s < 'a')
        {    
            buffer[i++] = 32;
            buffer[i++] = *s++ - 'A' + 'a';
        }
         else
            buffer[i++] = *s++;
    }
    buffer[i]=0;
    
    printf("%s",buffer);
    
    s = ptr;
    for(;i;i--)
        *(s+i) = buffer[i];
    *s = buffer[0];
    return s; 
}