80 lines
1.5 KiB
Go
80 lines
1.5 KiB
Go
package main
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import (
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"fmt"
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"math/rand"
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"time"
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)
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type matrix [][]int
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func shuffle(row []int, n int) {
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rand.Shuffle(n, func(i, j int) {
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row[i], row[j] = row[j], row[i]
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})
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}
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func latinSquare(n int) {
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if n <= 0 {
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fmt.Println("[]\n")
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return
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}
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latin := make(matrix, n)
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for i := 0; i < n; i++ {
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latin[i] = make([]int, n)
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if i == n-1 {
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break
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}
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for j := 0; j < n; j++ {
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latin[i][j] = j
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}
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}
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// first row
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shuffle(latin[0], n)
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// middle row(s)
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for i := 1; i < n-1; i++ {
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shuffled := false
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shuffling:
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for !shuffled {
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shuffle(latin[i], n)
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for k := 0; k < i; k++ {
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for j := 0; j < n; j++ {
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if latin[k][j] == latin[i][j] {
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continue shuffling
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}
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}
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}
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shuffled = true
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}
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}
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// last row
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for j := 0; j < n; j++ {
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used := make([]bool, n)
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for i := 0; i < n-1; i++ {
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used[latin[i][j]] = true
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}
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for k := 0; k < n; k++ {
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if !used[k] {
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latin[n-1][j] = k
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break
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}
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}
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}
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printSquare(latin, n)
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}
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func printSquare(latin matrix, n int) {
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for i := 0; i < n; i++ {
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fmt.Println(latin[i])
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}
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fmt.Println()
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}
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func main() {
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rand.Seed(time.Now().UnixNano())
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latinSquare(5)
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latinSquare(5)
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latinSquare(10) // for good measure
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}
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