/*
Generate N random 1s in a zero-based matrix.
Strategy:
- Treat the matrix as a flat index space [0 until rows*cols].
- Randomly pick unique positions using a MutableSet to ensure uniqueness.
- Convert each chosen flat index back to (row, col).
- This avoids repeatedly searching for empty cells and keeps the logic simple.
*/
// Allocate a rows×cols matrix initialized to zero
fun allocateMatrix(rows: Int, cols: Int): Array<IntArray> {
// IntArray keeps memory compact and fast
return Array(rows) { IntArray(cols) { 0 } }
}
// Print the matrix
fun printMatrix(matrix: Array<IntArray>) {
matrix.forEach { row ->
println(row.joinToString(" "))
}
}
// Generate N random 1s in a zero-based matrix
fun generateRandomMatrix(rows: Int, cols: Int, count: Int): Array<IntArray> {
val total = rows * cols
if (count > total) {
throw IllegalArgumentException("Requested more 1s than available cells.")
}
val matrix = allocateMatrix(rows, cols)
// Use a MutableSet to ensure unique positions
val chosen: MutableSet<Int> = mutableSetOf()
// Draw unique positions
while (chosen.size < count) {
val index = (0 until total).random() // Kotlin's expressive random API
chosen += index
}
// Convert flat indices to (row, col)
for (index in chosen) {
val r = index / cols
val c = index % cols
matrix[r][c] = 1
}
return matrix
}
// Example usage
fun main() {
val rows = 5
val cols = 7
val numberOfOnes = 10
val result = generateRandomMatrix(rows, cols, numberOfOnes)
printMatrix(result)
}
/*
run:
1 1 0 1 0 1 0
0 0 0 0 0 1 0
1 0 0 0 0 0 1
1 1 0 0 0 0 0
0 0 0 1 0 0 0
*/
