package main
import (
"fmt"
)
// Swap two elements in a slice
func swap(arr []rune, i, j int) {
arr[i], arr[j] = arr[j], arr[i]
}
// Print slice of runes
func printArray(arr []rune) {
for _, ch := range arr {
fmt.Printf("%c ", ch)
}
fmt.Println()
}
// Recursive function to generate permutations
func permute(arr []rune, l, r int) {
if l == r {
printArray(arr)
return
}
for i := l; i <= r; i++ {
swap(arr, l, i)
permute(arr, l + 1, r)
swap(arr, l, i) // backtrack
}
}
// Generate all combinations using bitmask
func generateCombinations(arr []rune) {
size := len(arr)
for mask := 1; mask < (1 << size); mask++ {
for i := 0; i < size; i++ {
if mask & (1 << i) != 0 {
fmt.Printf("%c ", arr[i])
}
}
fmt.Println()
}
}
func main() {
input := []rune("abc")
size := len(input)
fmt.Println("All permutations:")
permute(input, 0, size-1)
fmt.Println("\nAll combinations:")
generateCombinations(input)
}
/*
run:
All permutations:
a b c
a c b
b a c
b c a
c b a
c a b
All combinations:
a
b
a b
c
a c
b c
a b c
*/
