#3379

Easy

LeetCode Problem Workspace

Transformed Array

Simulate operations on a circular array to return a transformed result array following specific rules.

Problem Statement

You are given an integer array nums, which represents a circular array. Your task is to create a new array result that is the same size as nums, following specific transformation rules.

In a circular array, moving past the last element wraps around to the beginning. Similarly, moving before the first element wraps back to the end. Based on these rules, create the result array and return it.

Examples

Example 1

Input: nums = [3,-2,1,1]

Output: [1,1,1,3]

Example 2

Input: nums = [-1,4,-1]

Output: [-1,-1,4]

Constraints

1 <= nums.length <= 100
-100 <= nums[i] <= 100

Solution Approach

Simulate Array Transformation

To solve the problem, iterate over the elements of the array and apply the circular transformation rule. For each element, account for the circular nature of the array and place the transformed value into the correct position in the result array.

Handle Circular Indexing

When accessing an index in the array, use modular arithmetic to simulate the wraparound behavior. This ensures that indices greater than the length of the array wrap back to the beginning, making it behave as a circular array.

Efficient Memory Usage

Since the problem involves transforming an array in a circular fashion, ensure that the solution uses a space-efficient approach to hold the result without unnecessary additional memory usage. Focus on using a direct mapping to avoid extra copies of data.

Complexity Analysis

Metric	Value
Time	Depends on the final approach
Space	Depends on the final approach

The time complexity of the problem depends on the final approach, but it typically involves iterating through the array once, resulting in O(n) time complexity. The space complexity is also O(n) due to the need to store the result array, where n is the length of the input array.

What Interviewers Usually Probe

The candidate demonstrates a solid understanding of array indexing and modular arithmetic.
The candidate can effectively simulate circular array behavior with minimal memory usage.
The candidate can write a time-efficient solution while correctly handling circular array traversal.

Common Pitfalls or Variants

Common pitfalls

Not using modular arithmetic correctly to handle the circular indexing.
Overcomplicating the solution with unnecessary data structures.
Failing to account for the circular nature of the array, causing incorrect mappings in the result array.

Follow-up variants

Simulating different transformations based on different rules while keeping the array circular.
Handling different array sizes, such as large inputs beyond the typical size constraints.
Modifying the circular transformation rules, such as shifting values based on additional constraints.

FAQ

What is the main pattern behind the Transformed Array problem?

The problem revolves around simulating a circular array transformation by applying modular arithmetic to handle the wraparound behavior.

What are common mistakes to avoid in this problem?

Not accounting for the circular nature of the array is a common mistake, leading to incorrect array indexing and wrong results.

How can I improve the space complexity of my solution?

Focus on directly modifying the result array without using extra data structures or creating unnecessary copies of the array.

What time complexity can I expect for this problem?

The typical time complexity for this problem is O(n), as we only need to iterate through the array once to apply the transformations.

What if the array length is very large?

Even with large arrays, the problem's linear time complexity ensures that the solution remains efficient as long as memory usage is optimized.

terminal

Solution

Solution 1: Simulation

We create a result array $\textit{ans}$. For each index, we move right or left $|nums[i]|$ steps based on whether $nums[i]$ is positive or negative, calculate the landing index, and assign the value at that index to $\textit{ans}[i]$.

1

2

3

4

class Solution:
    def constructTransformedArray(self, nums: List[int]) -> List[int]:
        n = len(nums)
        return [nums[(i + x % n + n) % n] for i, x in enumerate(nums)]

Continue Practicing

#3354 make array elements equal to zero #3417 zigzag grid traversal with skip #3433 count mentions per user