problem

We have two special characters:

  • The first character can be represented by one bit 0.
  • The second character can be represented by two bits (10 or 11).

Given a binary array bits that ends with 0, return true if the last character must be a one-bit character.

 

Example 1:

Input: bits = [1,0,0]
Output: true
Explanation: The only way to decode it is two-bit character and one-bit character.
So the last character is one-bit character.

Example 2:

Input: bits = [1,1,1,0]
Output: false
Explanation: The only way to decode it is two-bit character and two-bit character.
So the last character is not one-bit character.

 

Constraints:

  • 1 <= bits.length <= 1000
  • bits[i] is either 0 or 1.

submission

impl Solution {
    pub fn is_one_bit_character(bits: Vec<i32>) -> bool {
        // solution count 1s from the right end
        bits.into_iter()
            .rev()
            .skip(1)
            .take_while(|&b| b == 1)
            .count() % 2 == 0
    }
}