#code/dsa/two_pointers

832 Flipping an Image

Problem Statement

Given an n x n binary matrix image, 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].

Input: image = [[1,1,0],[1,0,1],[0,0,0|1,1,0],[1,0,1],[0,0,0]]
Output: [[1,0,0],[0,1,0],[1,1,1|1,0,0],[0,1,0],[1,1,1]]

Approach

Loop through the array, init two pointers, one at the beginning, one at the end, while loop through, swap position and invert via 1 -

Solution

var flipAndInvertImage = function(image) {
	for (const img of image) {
		let l = 0,
			r = img.length - 1
		while (l <= r) {
			[img[l], img[r]] = [1 - img[r], 1 - img[l]];
			l++
			r--
		}
	}
  
	return image
};

Questions

References