What is the time complexity of LeetCode 2450. Number of Distinct Binary Strings After Applying Operations?

The Python solution on this page runs in O(n).

What is the space complexity of LeetCode 2450. Number of Distinct Binary Strings After Applying Operations?

The Python solution on this page uses O(1) auxiliary space.

Number of Distinct Binary Strings After Applying Operations — LeetCode 2450 Python Solution

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Problem: #2450
Pattern: Math and Number Theory
Reading time: 2 min
Source: leetcode.com

The problem

You are given a binary string s and a positive integer k. You can apply the following operation on the string any number of times: Choose any substring of size k from s and flip all its characters, that is, turn all 1's into 0's, and all 0's into 1's.

Example

Input: s = "1001", k = 3
Output: 4
Explanation: We can obtain the following strings:

Python solution

Python

class Solution:
    def countDistinctStrings(self, s: str, k: int) -> int:
        return pow(2, len(s) - k + 1) % (10**9 + 7)

Complexity

Measure	Complexity
Time	O(n)
Space	O(1) auxiliary

Pattern: Math and Number Theory

Find the closed form, the invariant, or the modular identity — and skip the loop entirely. LeetCode 2450. Number of Distinct Binary Strings After Applying Operations is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Math.

The math and number theory guide has the Python template for the pattern and the 485 LeetCode problems that use it.

Frequently asked questions

How hard is LeetCode 2450. Number of Distinct Binary Strings After Applying Operations?: LeetCode 2450. Number of Distinct Binary Strings After Applying Operations is rated Medium on LeetCode.
What is the time complexity of LeetCode 2450. Number of Distinct Binary Strings After Applying Operations?: The Python solution on this page runs in O(n).
What is the space complexity of LeetCode 2450. Number of Distinct Binary Strings After Applying Operations?: The Python solution on this page uses O(1) auxiliary space.
What topics does LeetCode 2450. Number of Distinct Binary Strings After Applying Operations cover?: LeetCode 2450. Number of Distinct Binary Strings After Applying Operations is tagged Math and String on LeetCode.
Is LeetCode 2450. Number of Distinct Binary Strings After Applying Operations a premium problem?: Yes. LeetCode 2450. Number of Distinct Binary Strings After Applying Operations is a LeetCode Premium problem, so the full statement and test cases require a paid LeetCode subscription.