Sha256: 781c31bb74a8f2c20e7dd212211f3b56768c5bd7c4ac921393f62fcd78dfe707
Contents?: true
Size: 1.23 KB
Versions: 80
Compression:
Stored size: 1.23 KB
Contents
package railfence
import (
"sort"
)
type pair struct {
index, value int
letter byte
}
func pattern(rails, size int) []pair {
var pairs []pair
var v, direction = 0, 1
for i := 0; i < size; i++ {
pairs = append(pairs, pair{index: i, value: v})
v += direction
if v == 0 {
direction = 1
} else if v == rails-1 {
direction = -1
}
}
return pairs
}
func sortedPattern(rails, size int) []pair {
fence := pattern(rails, size)
sort.Slice(fence, func(i, j int) bool {
f1, f2 := fence[i], fence[j]
return f1.value < f2.value || (f1.value == f2.value && f1.index < f2.index)
})
return fence
}
// Encode encodes given message with given rails
func Encode(msg string, rails int) string {
fence := sortedPattern(rails, len(msg))
var encoded []byte
for _, p := range fence {
encoded = append(encoded, msg[p.index])
}
return string(encoded)
}
// Decode decodes given message with given rails
func Decode(msg string, rails int) string {
fence := sortedPattern(rails, len(msg))
for i := range msg {
fence[i].letter = msg[i]
}
sort.Slice(fence, func(i, j int) bool { return fence[i].index < fence[j].index })
var decoded []byte
for _, p := range fence {
decoded = append(decoded, p.letter)
}
return string(decoded)
}
Version data entries
80 entries across 80 versions & 1 rubygems