Palindrome practice

main.rs

#![feature(str_char)]

use std::ascii::AsciiExt;
use std::usize::MAX;

fn is_palindrome(s: &str) -> bool {
  assert!(s.is_ascii());

  let mid = s.len() / 2;
  let mut left_ptr = if s.len() % 2 == 0 { mid - 1 } else { mid };
  let mut right_ptr = if s.len() % 2 == 0 { mid } else { mid };

  while right_ptr < s.len() {
    if s.char_at(left_ptr) != s.char_at(right_ptr) {
      return false;
    }

    if left_ptr > 0 { left_ptr -= 1; }

    right_ptr += 1;
  } 

  return true;
}

fn min_splits(s: &str) -> usize {
  assert!(s.is_ascii());

  let mut min = MAX;

  if s.len() > 1 {
    for i in 1..s.len() + 1 {
      if is_palindrome(&s[0..i]) {
        let recurse = min_splits(&s[i..]);
        if recurse < min {
          min = if s[i..].len() == 0 { recurse } else { recurse + 1 };
        }
      }
    }

    min
  } else {
    0
  }
}

fn main() {
  assert!(is_palindrome("aba"));
  assert!(!is_palindrome("aaba"));
  assert!(!is_palindrome("ab"));
  assert!(is_palindrome("aaabaaa"));
  assert!(is_palindrome("aa"));
  assert_eq!(min_splits("aba"), 0);
  assert_eq!(min_splits("aabaaaab"), 1);
  assert_eq!(min_splits("aaba"), 1);
}