// Multiply rows of A by columns of B.
typealias Matrix = List<MutableList<Int>>
// Print a 2D array (matrix)
fun printMatrix(arr2d: Matrix) {
for (row in arr2d) {
for (value in row) {
print("%4d".format(value))
}
println()
}
}
// Multiply matrices A and B into C
fun multipleMatrix(a: Matrix, b: Matrix, c: Matrix) {
for (i in c.indices) {
for (j in c[i].indices) {
for (k in a[i].indices) {
c[i][j] += a[i][k] * b[k][j]
}
}
}
}
fun main() {
// Create matrices
val a: Matrix = listOf(
mutableListOf(1, 8, 5),
mutableListOf(6, 7, 1),
mutableListOf(8, 7, 6)
)
val b: Matrix = listOf(
mutableListOf(4, 8, 1),
mutableListOf(6, 5, 3),
mutableListOf(4, 6, 5)
)
// Initialize result matrix C with zeros
val c: Matrix = List(a.size) {
MutableList(b[0].size) { 0 }
}
// c[0][0] = (a[0][0] * b[0][0]) + (a[0][1] * b[1][0]) + (a[0][2] * b[2][0])
printMatrix(a)
println()
printMatrix(b)
println()
multipleMatrix(a, b, c)
printMatrix(c)
}
/*
run:
1 8 5
6 7 1
8 7 6
4 8 1
6 5 3
4 6 5
72 78 50
70 89 32
98 135 59
*/
