Is Check Balanced String easy or hard?

Check Balanced String is categorized as an Easy problem. The solution only requires basic string traversal, digit conversion, and conditional checks based on index parity.

Check Balanced String Python/Java solution

Both Python and Java implementations use the same logic: loop through the string, convert characters to digits, and update the correct sum based on index parity. The algorithm remains O(n) time and O(1) space across all languages including C++, JavaScript, and C#.

How to solve Check Balanced String in O(n)?

Iterate through the string from index 0 to n-1. Convert each character to its numeric value and add it to either the even-index sum or odd-index sum depending on i % 2. After the loop finishes, compare the two sums to determine whether the string is balanced.

What is the best approach for Check Balanced String?

The best approach is a single-pass iteration through the string while maintaining two sums for even and odd indices. Convert each character to a digit and update the correct sum based on index parity. This method runs in O(n) time and uses O(1) extra space.

Is Check Balanced String asked at Google/Amazon/Meta?

This problem reflects common string iteration and index-parity logic often seen in screening rounds. While the exact problem ID may not appear frequently, similar parity-sum and string traversal questions are common in interviews at large tech companies.

What data structure is used in Check Balanced String?

No additional data structure is required. The solution operates directly on the input string and uses two integer variables to track the running sums for even and odd indices.

What is the time complexity of Check Balanced String?

The time complexity is O(n) because the algorithm scans the string exactly once. Each character is processed with constant-time operations such as digit conversion and addition. Space complexity remains O(1) since only two counters are stored.

Description Solution Video 7:03

3340. Check Balanced String

Easy82.3% acceptance1 company

You are given a string num consisting of only digits. A string of digits is called balanced if the sum of the digits at even indices is equal to the sum of digits at odd indices.

Return true if num is balanced, otherwise return false.

Example 1:

Input: num = "1234"

Output: false

Explanation:

The sum of digits at even indices is 1 + 3 == 4, and the sum of digits at odd indices is 2 + 4 == 6.
Since 4 is not equal to 6, num is not balanced.

Example 2:

Input: num = "24123"

Output: true

Explanation:

The sum of digits at even indices is 2 + 1 + 3 == 6, and the sum of digits at odd indices is 4 + 2 == 6.
Since both are equal the num is balanced.

Constraints: