Problem 386365 · easy · Phase 03 Linear Management & Searching

Fewest Flips for a k-Run

sliding window · fixed-size window · binary arrays

A row of LEDs is described by bits, where 1 is on and 0 is off. You may flip individual LEDs on. Return the minimum number of flips needed so that some block of exactly k consecutive LEDs is entirely on.

Examples

Input:  bits = [1, 0, 0, 1, 1, 0, 1], k = 3
Output: 1
Explanation: the block [0, 1, 1] at indices 2..4 needs only one flip.

Input:  bits = [0, 0, 0], k = 2
Output: 2

Constraints

  • 1 <= k <= len(bits) <= 10**5
  • bits[i] is 0 or 1
  • Target complexity: O(n) time; recounting each window from scratch is too slow for the largest tests.

Goals

  • Count zeros inside a fixed window incrementally
  • Track the minimum across windows
Starting Python…