Find Latest Group of Size M
Given an array arr that represents a permutation of numbers from 1 to n.
You have a binary string of size n that initially has all its bits set to zero. At each step i (assuming both the binary string and arr are 1-indexed) from 1 to n, the bit at position arr[i] is set to 1.
You are also given an integer m. Find the latest step at which there exists a group of ones of length m. A group of ones is a contiguous substring of 1's such that it cannot be extended in either direction.
Return the latest step at which there exists a group of ones of length exactly m. If no such group exists, return -1.
Example 1
Input
arr = [3,5,1,2,4], m = 1Output
4The latest step at which there exists a group of size 1 is step 4.
Example 2
Input
arr = [3,1,5,4,2], m = 2Output
-1No group of size 2 exists during any step.
Constraints
- n == arr.length
- 1 <= m <= n <= 10^5
- 1 <= arr[i] <= n
- All integers in arr are distinct.