2460. Apply Operations to an Array

[iamAntimPal]

2460. Apply Operations to an Array

Difficulty: Easy
Topics: Arrays, Operations
Hint: Operations are applied sequentially, not simultaneously.

Problem Statement

You are given a 0-indexed array nums of size n consisting of non-negative integers.

You need to apply n - 1 operations to this array where, in the i-th operation (0-indexed), you will do the following on the i-th element of nums:

• If nums[i] == nums[i + 1], then multiply nums[i] by 2 and set nums[i + 1] to 0.
• Otherwise, skip the operation.

After performing all the operations, shift all the 0s to the end of the array.

For example, the array [1, 0, 2, 0, 0, 1] after shifting all its 0s to the end becomes [1, 2, 1, 0, 0, 0].

Return the resulting array.

Note: The operations are applied sequentially, not all at once.

Examples

Example 1

Input: nums = [1,2,2,1,1,0]
Output: [1,4,2,0,0,0]

Explanation:

• i = 0: nums[0] and nums[1] are not equal, so skip this operation.
• i = 1: nums[1] and nums[2] are equal, multiply nums[1] by 2 and set nums[2] to 0.
  Array becomes: [1,4,0,1,1,0].
• i = 2: nums[2] and nums[3] are not equal, skip.
• i = 3: nums[3] and nums[4] are equal, multiply nums[3] by 2 and set nums[4] to 0.
  Array becomes: [1,4,0,2,0,0].
• i = 4: nums[4] and nums[5] are equal, multiply nums[4] by 2 and set nums[5] to 0.
  Array remains: [1,4,0,2,0,0].

After shifting all 0s to the end, the result is [1,4,2,0,0,0].

Example 2

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

Explanation:
No operation can be applied. Simply shift the 0 to the end.

Constraints

• 2 <= nums.length <= 2000
• 0 <= nums[i] <= 1000

Discussion

I'm looking for the most efficient approach to solve this problem while handling edge cases such as multiple adjacent equal numbers. Some points for discussion:

• Sequential Operations: How do we ensure that operations applied on one index don’t affect subsequent operations unexpectedly?
• Zero Shifting: Is there an optimal method to shift zeros to the end without using extra space?
• Time Complexity: Can we optimize the overall process to run in a single pass?

I’d love to hear your thoughts, optimizations, or alternative implementations for this problem. Please share your solutions and ideas below!

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Feel free to start a discussion and share your implementations. Let’s collaborate and learn together!