832. Flipping an Image

Problem Statement

Flipping an Image - LeetCode

Pattern:

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Solution

public int[][] flipAndInvertImage(int[][] A) {
	int n = A.length;
	for (int[] row : A)
		for (int i = 0; i * 2 < n; i++)
			if (row[i] == row[n - i - 1])
				row[i] = row[n - i - 1] ^= 1;
	return A;
}

Notes

row[i] = row[n - i - 1] ^= 1

can be rewritten as,

row[i] = row[n - i - 1] = row[n - i - 1] ^ 1

can be rewritten as, executed in sequence,

row[n - i - 1] = row[n - i - 1] ^ 1
row[i] = row[n - i - 1]

a ^= b equals a = a ^ b
bit manipulation by XOR: https://en.wikipedia.org/wiki/XOR_gate