How do you solve Flipping an Image on LeetCode?

Flipping an Image (LeetCode #832) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(n) time complexity and O(1) space complexity. Key insight: Flipping and inverting can be combined into a single operation.

What is the brute force solution for Flipping an Image?

The brute force approach for Flipping an Image is Brute Force, with O(n²) time complexity and O(1) space complexity. The brute force approach involves two straightforward operations: first reversing each row of the matrix and then inverting the values. This is simple to understand and implement, making it a good starting point. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Flipping an Image?

Flipping an Image uses the following concepts: Array, Two Pointers, Bit Manipulation, Matrix, Simulation. The recommended patterns to study are: Array, Two Pointers.

What are the interview tips for Flipping an Image?

Explain your thought process clearly as you write code. Discuss the time and space complexity of your solution. Consider edge cases, such as the smallest possible matrix.

What are common mistakes when solving Flipping an Image?

Not considering the in-place modification of the array. Confusing the order of operations (flip vs invert).

#832

Flipping an Image

Easy

ArrayTwo PointersBit ManipulationMatrixSimulationArrayTwo Pointers

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n²)	O(n)
Space	O(1)	O(1)

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Intuition

Time O(n)Space O(1)

The optimal solution combines the flipping and inverting operations into a single pass through each row. This reduces the number of iterations needed, making the solution more efficient.

⚙️

Algorithm

2 steps

1Step 1: For each row, iterate through the first half of the row.
2Step 2: Swap the elements at the current index and its mirrored index, while simultaneously inverting their values.

solution.py8 lines

1# Full working Python code
2
3def flipAndInvertImage(image):
4    n = len(image)
5    for row in image:
6        for j in range((n + 1) // 2):
7            row[j], row[n - 1 - j] = 1 - row[n - 1 - j], 1 - row[j]
8    return image

ℹ

Complexity note: The time complexity is O(n) because we only iterate through half of each row, making it more efficient than the brute force approach. The space complexity remains O(1) as we are still modifying the matrix in place.

1Flipping and inverting can be combined into a single operation.
2Understanding how to manipulate arrays in place is crucial.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.