Is 1-bit and 2-bit Characters easy or hard?

LeetCode classifies this problem as Easy. The logic is straightforward once you recognize that 1 starts a two-bit character and 0 stands alone. The challenge mainly involves correctly simulating the traversal and handling the final element check.

1-bit and 2-bit Characters Python/Java solution

In Python or Java, implement a loop with an index variable. Increment the index by 1 if the current element is 0, otherwise increment by 2. After the loop finishes, check whether the index stopped exactly at the last element to determine if it represents a 1-bit character.

How to solve 1-bit and 2-bit Characters in O(n)?

Traverse the array with an index pointer. When you see a 0, move one step; when you see a 1, skip the next bit because it forms a 2-bit character. Continue until reaching the end. If the pointer lands exactly on the final index, the last character is a 1-bit character.

What is the best approach for 1-bit and 2-bit Characters?

The traversal and check approach is the most common solution. Iterate through the array and move one step for a 0 (1-bit character) or two steps for a 1 (start of a 2-bit character). If the pointer ends exactly on the last index, the last character is a 1-bit character. This runs in O(n) time with O(1) space.

Is 1-bit and 2-bit Characters asked at Google/Amazon/Meta?

Problems involving binary encoding patterns and array traversal appear frequently in interviews at companies like Google, Amazon, and Meta. This specific problem is commonly used in coding practice platforms to test array scanning logic and greedy reasoning.

What data structure is used in 1-bit and 2-bit Characters?

The problem primarily uses a simple array of integers representing bits. The algorithm relies on sequential traversal and pointer movement rather than additional data structures such as hash maps or stacks.

What is the time complexity of 1-bit and 2-bit Characters?

The optimal solutions run in O(n) time because the array is scanned once. Each step either advances the pointer by one or two positions. Space complexity remains O(1) since the algorithm uses only a few variables and no additional data structures.

Description Hints 1 Solution Video 16:59

717. 1-bit and 2-bit Characters

Easy49.5% acceptance4 companies

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: