package LeetCode_717
/**
* 717. 1-bit and 2-bit Characters
* https://leetcode.com/problems/1-bit-and-2-bit-characters/
*
* 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).
Now given a string represented by several bits. Return whether the last character must be a one-bit character or not.
The given string will always end with a zero.
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.
Note:
1. 1 <= len(bits) <= 1000.
2. bits[i] is always 0 or 1.
* */
class Solution {
/*
* solution: scan array from left to right, check the pointer if can go to the end;
* if current number is 0, pointer++;
* if current is 1, pointer+=2, because (1,0) or (1,0) is valid;
* Time complexity:O(n), Space complexity:O(1)
* */
fun isOneBitCharacter(bits: IntArray): Boolean {
var i = 0
val n = bits.size
while (i < n - 1) {
if (bits[i] == 1) {
i += 2
} else {
i++
}
}
return i == n - 1
}
}
