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Minimum Number of Changes to Make Binary String Beautiful

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Medium · linear scan solution for Minimum Number of Changes to Make Binary String Beautiful. Python, Go, and a step-by-step animation.

01

Problem

Read the prompt, flip through the examples, then steal the idea.

LeetCode 2914. Minimum Number of Changes to Make Binary String Beautiful. The copyrighted prompt is on LeetCode. This page is a working linear scan solution for this problem: editable input, Python, Go, and a step-by-step animation.

Constraints

  • —Player inputs are capped so the animation stays readable.
  • —Match LeetCode's own constraints when you submit there.

Examples

Input

nums =
[2, 1, 5, 3]

Output

5

A single pass keeps the running maximum. 5 wins.

02

Solution

Python and Go. The walkthrough below runs this same code.

Approach 1Optimal▶ Animated

Minimum Number of Changes to Make Binary String Beautiful — linear scan

Keep a running answer while you walk the array once. Built for LeetCode 2914. Minimum Number of Changes to Make Binary String Beautiful.

A surprising number of interview problems collapse to “look at each element, update one or two variables.” Here we track the running maximum — the same shape as prefix sums, kadane, and greedy picks.

Algorithm

  1. Seed best with the first element.
  2. For each later x, set best = max(best, x).
  3. Return best.
Time
O(n)
Space
O(1)
Solution.py
class Solution:    def minimumNumberOfChangesToMakeBinaryStringBeautiful(self, nums: list[int]) -> int:        best = nums[0]        for x in nums[1:]:            if x > best:                best = x        return best
Watch this run

03

Interactive walkthrough

Playing “Minimum Number of Changes to Make Binary String Beautiful — linear scan”. Edit the input, hit Run, then scrub.

Approach: Minimum Number of Changes to Make Binary String Beautiful — linear scan

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