package main
import (
"fmt"
"math/rand"
"time"
)
/*
Generate N random 1s in a zero-based matrix.
Strategy:
- Treat the matrix as a flat index space [0 .. rows*cols - 1].
- Randomly pick unique positions using a map[ int ]bool to ensure uniqueness.
- Convert each chosen flat index back to (row, col).
- This avoids repeatedly searching for empty cells and keeps the logic simple.
*/
// allocateMatrix creates a rows×cols matrix initialized to zero.
func allocateMatrix(rows int, cols int) [][]int {
matrix := make([][]int, rows)
for r := 0; r < rows; r++ {
matrix[r] = make([]int, cols) // automatically initialized to zero
}
return matrix
}
// printMatrix prints the matrix row by row.
func printMatrix(matrix [][]int) {
for _, row := range matrix {
for _, v := range row {
fmt.Printf("%d ", v)
}
fmt.Println()
}
}
// generateRandomMatrix places N random 1s in a zero-based matrix.
func generateRandomMatrix(rows int, cols int, count int) [][]int {
total := rows * cols
if count > total {
panic("Requested more 1s than available cells.")
}
matrix := allocateMatrix(rows, cols)
// Use a map to ensure unique positions
chosen := make(map[int]bool)
rand.Seed(time.Now().UnixNano())
// Draw unique positions
for len(chosen) < count {
index := rand.Intn(total)
chosen[index] = true
}
// Convert flat indices to (row, col)
for index := range chosen {
r := index / cols
c := index % cols
matrix[r][c] = 1
}
return matrix
}
func main() {
rows := 5
cols := 7
numberOfOnes := 10
result := generateRandomMatrix(rows, cols, numberOfOnes)
printMatrix(result)
}
/*
run:
0 0 1 0 0 0 0
0 1 0 1 0 1 1
0 0 0 0 0 0 0
1 0 0 1 0 0 0
1 0 0 1 0 0 1
*/
