Repeat Within Reach

Easy

A turnstile logs badge numbers ids in the order people pass through. It looks suspicious when the same badge is scanned twice too close together. Return True if there are two different positions i and j with ids[i] == ids[j] and |i - j| ≤ reach. Otherwise return False.

Example 1

ids=[7, 3, 9, 7], reach=3 → True

Badge 7 was scanned at positions 0 and 3: 3 apart, which is within reach.

Example 2

ids=[7, 3, 9, 7], reach=2 → False

Same two scans, but now only a distance of 2 is allowed.

Example 3

ids=[4, 4], reach=0 → False

Constraints

1 ≤ len(ids) ≤ 10⁵
-10⁹ ≤ ids[i] ≤ 10⁹
0 ≤ reach ≤ 10⁵

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Topics

Array Hash Table Sliding Window

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Input

ids=[7, 3, 9, 7], reach=3

Expected

True

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