LeetCode 168. Excel Sheet Column Title

    1 -> A
    2 -> B
    3 -> C
    ...
    26 -> Z
    27 -> AA
    28 -> AB 

char* convertToTitle(int n) {
    int tmp = n;
    int i = 0;
    char *str = NULL;
    
    while(tmp > 0) {
        i++;
        tmp = (tmp-1)/26;
    }
    
    str = (char *) malloc(i*sizeof(char));
    tmp = n;
    
    for(; i>0; i--) {
        str[i-1] = (tmp-1)%26+‘A‘;
        tmp =(tmp-1)/26;
    }
    
    return str;
}