- Difficulty: Medium
- Tags: LeetCode, Medium, Greedy, Array, Hash Table, Counting, leetcode-2170, O(n), Freq Table
Problem
You are given a 0-indexed array nums
consisting of n
positive integers.
The array nums
is called alternating if:
nums[i - 2] == nums[i]
, where2 <= i <= n - 1
.nums[i - 1] != nums[i]
, where1 <= i <= n - 1
.
In one operation, you can choose an index i
and change nums[i]
into any positive integer.
Return the minimum number of operations required to make the array alternating.
Example 1:
Input: nums = [3,1,3,2,4,3] Output: 3 Explanation: One way to make the array alternating is by converting it to [3,1,3,1,3,1]. The number of operations required in this case is 3. It can be proven that it is not possible to make the array alternating in less than 3 operations.
Example 2:
Input: nums = [1,2,2,2,2] Output: 2 Explanation: One way to make the array alternating is by converting it to [1,2,1,2,1]. The number of operations required in this case is 2. Note that the array cannot be converted to [2,2,2,2,2] because in this case nums[0] == nums[1] which violates the conditions of an alternating array.
Constraints:
1 <= nums.length <= 105
1 <= nums[i] <= 105