import Foundation
/*
Generate N random 1s in a zero-based matrix.
Strategy:
- Treat the matrix as a flat index space [0 ..< rows*cols].
- Randomly pick unique positions using a Set 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
func allocateMatrix(rows: Int, cols: Int) -> [[Int]] {
// Array(repeating:) keeps the code compact and expressive
Array(repeating: Array(repeating: 0, count: cols), count: rows)
}
// Print the matrix
func printMatrix(_ matrix: [[Int]]) {
for row in matrix {
print(row.map(String.init).joined(separator: " "))
}
}
// Generate N random 1s in a zero-based matrix
func generateRandomMatrix(rows: Int, cols: Int, count: Int) -> [[Int]] {
let total = rows * cols
if count > total {
fatalError("Requested more 1s than available cells.")
}
var matrix = allocateMatrix(rows: rows, cols: cols)
// Use a Set to ensure unique positions
var chosen = Set<Int>()
// Draw unique positions
while chosen.count < count {
let index = Int.random(in: 0..<total)
chosen.insert(index)
}
// Convert flat indices to (row, col)
for index in chosen {
let r = index / cols
let c = index % cols
matrix[r][c] = 1
}
return matrix
}
// Example usage
let rows = 5
let cols = 7
let numberOfOnes = 10
let result = generateRandomMatrix(rows: rows, cols: cols, count: numberOfOnes)
printMatrix(result)
/*
run:
0 0 0 0 0 0 0
0 0 1 1 0 1 0
0 0 0 1 0 1 0
0 1 0 1 0 0 1
1 1 0 0 0 0 0
*/
