flipping-an-image.js

/**
 * Flipping an Image
 *
 * 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 0 is replaced by 1, and each 1 is replaced by 0.
 * 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] <= 1
 */

/**
 * @param {number[][]} A
 * @return {number[][]}
 */
const flipAndInvertImage = A => {
  for (let row of A) {
    for (let i = 0; i * 2 < row.length; i++) {
      if (row[i] === row[row.length - i - 1]) {
        row[i] = row[row.length - i - 1] ^= 1;
      }
    }
  }
  return A;
};

export { flipAndInvertImage };