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Problem: K Empty Slots

Medium
30 min
Explore the K Empty Slots problem where you determine the earliest day two bulbs are switched on with exactly k bulbs turned off between them. This lesson helps you understand pattern recognition for coding interviews and implement solutions in practice coding environments.

Statement

You are given nn bulbs arranged in a row, numbered from 11 to nn. Initially, all bulbs are turned off.

Each day, exactly one bulb is switched on. You are given an array, bulbs of length nn where bulbs[i] =x= x means that on day i+1i + 1 (1‑indexed), the bulb at position xx (also 1‑indexed) is turned on.

So, given an integer k, determine the earliest day (the smallest day number) on which there are two bulbs that are on such that exactly k bulbs are off between them.

If no such day exists, return 1-1.

Constraints:

  • n==n == bulbs.length

  • 1n1031 \leq n \leq 10^3

  • 11 \leq bulbs[i] n\leq n

  • bulbs is a permutationIt is a sequence that contains every integer from 1 to n exactly once and in any order. of numbers from 11 to nn

  • 00 \leq k 103\leq 10^3

Problem
Ask
Submissions

Problem: K Empty Slots

Medium
30 min
Explore the K Empty Slots problem where you determine the earliest day two bulbs are switched on with exactly k bulbs turned off between them. This lesson helps you understand pattern recognition for coding interviews and implement solutions in practice coding environments.

Statement

You are given nn bulbs arranged in a row, numbered from 11 to nn. Initially, all bulbs are turned off.

Each day, exactly one bulb is switched on. You are given an array, bulbs of length nn where bulbs[i] =x= x means that on day i+1i + 1 (1‑indexed), the bulb at position xx (also 1‑indexed) is turned on.

So, given an integer k, determine the earliest day (the smallest day number) on which there are two bulbs that are on such that exactly k bulbs are off between them.

If no such day exists, return 1-1.

Constraints:

  • n==n == bulbs.length

  • 1n1031 \leq n \leq 10^3

  • 11 \leq bulbs[i] n\leq n

  • bulbs is a permutationIt is a sequence that contains every integer from 1 to n exactly once and in any order. of numbers from 11 to nn

  • 00 \leq k 103\leq 10^3