package q219

func containsNearbyDuplicate(nums []int, k int) bool {
	seen := make(map[int]struct{}, k)

	for i, num := range nums {
		if _, ok := seen[num]; ok {
			return true
		}
		seen[num] = struct{}{}
		if i >= k {
			delete(seen, nums[i-k])
		}
	}
	return false
}

var _ = containsNearbyDuplicate