find-the-largest-almost-missing-integer

You are given an integer array nums and an integer k.

An integer x is almost missing from nums if x appears in exactly one subarray of size k within nums.

Return the largest almost missing integer from nums. If no such integer exists, return -1.

Example 1:

Input: nums = [3,9,2,1,7], k = 3

Output: 7

Explanation:

• 1 appears in 2 subarrays of size 3: [9, 2, 1] and [2, 1, 7].


• 2 appears in 3 subarrays of size 3: [3, 9, 2], [9, 2, 1], [2, 1, 7].


• 3 appears in 1 subarray of size 3: [3, 9, 2].


• 7 appears in 1 subarray of size 3: [2, 1, 7].


• 9 appears in 2 subarrays of size 3: [3, 9, 2], and [9, 2, 1].

We return 7 since it is the largest integer that appears in exactly one subarray of size k.

Example 2:

Input: nums = [3,9,7,2,1,7], k = 4

Output: 3

Explanation:

• 1 appears in 2 subarrays of size 4: [9, 7, 2, 1], [7, 2, 1, 7].


• 2 appears in 3 subarrays of size 4: [3, 9, 7, 2], [9, 7, 2, 1], [7, 2, 1, 7].


• 3 appears in 1 subarray of size 4: [3, 9, 7, 2].


• 7 appears in 3 subarrays of size 4: [3, 9, 7, 2], [9, 7, 2, 1], [7, 2, 1, 7].


• 9 appears in 2 subarrays of size 4: [3, 9, 7, 2], [9, 7, 2, 1].

We return 3 since it is the largest and only integer that appears in exactly one subarray of size k.

Example 3:

Input: nums = [0,0], k = 1

Output: -1

Explanation:

There is no integer that appears in only one subarray of size 1.

Constraints:

• 1 <= nums.length <= 50


• 0 <= nums[i] <= 50


• 1 <= k <= nums.length