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Rotate Image

Explore how to rotate an n by n matrix 90 degrees clockwise in place, modifying the original matrix without extra memory. This lesson helps you understand matrix traversal and in-place transformations, key skills for technical coding interviews.

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Statement

Given an n×nn \times n matrix, rotate the matrix 90 degrees clockwise. The performed rotation should be in place, i.e., the given matrix is modified directly without allocating another matrix.

Note: The function should only return the modified input matrix.

Constraints:

  • matrix.length == matrix[i].length
  • 1≤1 \leq matrix.length ≤20\leq 20
  • −103≤-10^3 \leq matrix[i][j] ≤103\leq 10^3

Examples

Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

Rotate Image

1.

What is the output if the following matrix is given as input?

matrix = [[2, 6, 8],
                  [3, 4, 8],
                  [9, 8, 8]]

A.

[[8, 8, 9],
  [8, 4, 3],
  [8, 6, 2]]

B.

[[8, 8, 8],
  [6, 4, 8],
  [2, 3, 9]]

C.

[[9, 3, 2],
  [8, 4, 6],
  [8, 8, 8]]

D.

[[8, 8, 9],
  [8, 6, 2],
  [8, 4, 3]]

1 / 3

Figure it out!

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Sequence - Vertical
Drag and drop the cards to rearrange them in the correct sequence.
1
2
3
4
5

Try it yourself

Implement your solution in the following coding playground:

Java
usercode > RotateImage.java
import java.util.*;
public class RotateImage {
    public static int[][] rotateImage(int[][] matrix) {
        // Replace this placeholder return statement with your code
        return matrix;
    }
}
Rotate Image