I provided algorithm with O(n2) complexity. They he asked for optimizing it for speed. I gave another algorithm with O(nlogn) that involves mergesort of individual strings and then one-to-one comparison. Everyone can have their own algorithms and he wanted me provide algorithm as he had in his mind... he kept asking for O(n) solution that i could not completely provide in given amount of time...

char *str = "civic"; char* begin = str; char* end = str + strlen(str) - 1; int is_palindrome = 1; while ( begin < end ) { if ( to_upper(*begin) == to_upper(*end)) continue; else { is_palindrome = 0; break; } }