01-08 - Zero Matrix [Cracking the Coding Interview]

function zeroMatrix(matrix) {
	const m = matrix.length,
		n = matrix[0] && matrix[0].length

	if (!m || !n) return false

	const zeroRows = {},
		zeroCols = {}

	//look for zeroes
	for (let row = 0; row < m; row++) {
		for (let col = 0; col < n; col++) {
			const cell = matrix[row][col]
			if (cell === 0) {
				zeroRows[row] = true
				zeroCols[col] = true
			}
		}
	}

	// Zero out rows
	for (const row of Object.keys(zeroRows)) {
		for (let col = 0; col < n; col++) {
			matrix[row][col] = 0
		}
	}

	// Zero out columns
	for (const col of Object.keys(zeroCols)) {
		for (let row = 0; row < m; row++) {
			matrix[row][col] = 0
		}
	}

	return matrix
}

/*
Matrix (m x n)
Time Complexity - O(m x n)
Space complexity - O(z). z is the number of zeros (x 2)
*/

// Tests
const testCases = [
	[
		[
			[7, 1, 2, 3, 4],
			[4, 5, 6, 0, 2],
			[8, 9, 3, 1, 3],
			[2, 0, 4, 5, 9],
			[3, 5, 2, 0, 3],
		],
		[
			[7, 0, 2, 0, 4],
			[0, 0, 0, 0, 0],
			[8, 0, 3, 0, 3],
			[0, 0, 0, 0, 0],
			[0, 0, 0, 0, 0],
		],
	],
	[
		[
			[1, 1, 1, 1],
			[1, 1, 1, 1],
			[1, 0, 1, 1],
			[1, 1, 1, 1],
			[1, 1, 1, 1],
			[1, 1, 1, 1],
		],
		[
			[1, 0, 1, 1],
			[1, 0, 1, 1],
			[0, 0, 0, 0],
			[1, 0, 1, 1],
			[1, 0, 1, 1],
			[1, 0, 1, 1],
		],
	],
]

for (const test of testCases) {
	console.log(zeroMatrix(test[0]).toString() === test[1].toString())
}