How to Flip a Binary Matrix in Java

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The challenge

Given a binary matrix A, we want to flip the image horizontally, then invert it, and return the resulting image.

To flip an image horizontally means that each row of the image is reversed.  For example, flipping [1, 1, 0] horizontally results in [0, 1, 1].

To invert an image means that each  is replaced by `1`, and each `1` is replaced by . For example, inverting [0, 1, 1] results in [1, 0, 0].

Example 1:

Input: [[1,1,0],[1,0,1],[0,0,0]]
Output: [[1,0,0],[0,1,0],[1,1,1]]
Explanation: First reverse each row: [[0,1,1],[1,0,1],[0,0,0]].
Then, invert the image: [[1,0,0],[0,1,0],[1,1,1]]

Example 2:

Input: [[1,1,0,0],[1,0,0,1],[0,1,1,1],[1,0,1,0]]
Output: [[1,1,0,0],[0,1,1,0],[0,0,0,1],[1,0,1,0]]
Explanation: First reverse each row: [[0,0,1,1],[1,0,0,1],[1,1,1,0],[0,1,0,1]].
Then invert the image: [[1,1,0,0],[0,1,1,0],[0,0,0,1],[1,0,1,0]]

Notes:

  • 1 <= A.length = A[0].length <= 20
  • 0 <= A[i][j]&nbsp;<=&nbsp;1

The solution in Java code

class Solution {
    public int[][] flipAndInvertImage(int[][] A) {
        for(int i = 0; i < A.length; i ++) {
            int j = 0;
            int k = A[i].length - 1;
            
            while(j <= k) {
                if(A[i][j] == 1) A[i][j] = 0;
                else A[i][j] = 1;

                if(k > j) {
                    if(A[i][k] == 1) A[i][k] = 0;
                    else A[i][k] = 1;

                    int temp = A[i][j];
                    A[i][j] = A[i][k];

                    A[i][k] = temp;
                }
                j++;
                k--;
            }
        }
        return A;
    }
}
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Andrew

Andrew is a visionary software engineer and DevOps expert with a proven track record of delivering cutting-edge solutions that drive innovation at Ataiva.com. As a leader on numerous high-profile projects, Andrew brings his exceptional technical expertise and collaborative leadership skills to the table, fostering a culture of agility and excellence within the team. With a passion for architecting scalable systems, automating workflows, and empowering teams, Andrew is a sought-after authority in the field of software development and DevOps.

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