package main

func setZeroes(matrix [][]int) {
	// Can use type 'map[int]struct{}' instead,
	// and insert empty struct like 'struct{}{}'.
	// Use 'if _, ok := m[key]; ok {}' to check.
	rows, cols := map[int]bool{}, map[int]bool{}
	for y, row := range matrix {
		for x, v := range row {
			if v == 0 {
				rows[y] = true
				cols[x] = true
			}
		}
	}
	for y, row := range matrix {
		for x := range row {
			if cols[x] || rows[y] {
				matrix[y][x] = 0
			}
		}
	}
}

/* func main() {
	m1 := [][]int{
		{0, 2, 4, 6},
		{1, 3, 4, 5},
		{6, 4, 0, 7},
		{4, 8, 9, 3},
	}
	setZeroes(m1)
	fmt.Println(m1)
}
*/