95 lines
1.8 KiB
Go
95 lines
1.8 KiB
Go
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package main
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import "math"
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var (
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alphabet = []rune("АБВГДЕЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯ")
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alphabetLen = len(alphabet)
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alphabetFreq = []float64{ // took from https://dpva.ru/Guide/GuideUnitsAlphabets/Alphabets/FrequencyRuLetters/ (without Ë)
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0.080159, // А
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0.015942, // Б
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0.045400, // ...
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0.016957,
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0.029801,
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0.084523,
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0.009398,
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0.016492,
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0.073559,
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0.012090,
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0.034952,
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0.044013,
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0.032080,
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0.066997,
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0.109714,
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0.028117,
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0.047352,
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0.054698,
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0.062606,
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0.026225,
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0.002645,
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0.009710,
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0.004829,
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0.014453,
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0.007283,
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0.003608,
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0.000367,
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0.018999,
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0.017392,
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0.003188,
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0.006377,
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0.020074,
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}
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mostFrequest = []rune("ОЕАИНТСРВЛК")
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)
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type Coder struct {
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ToCode map[rune]int
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ToRune map[int]rune
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RuFreq map[rune]float64
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}
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func NewCoder() Coder {
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coder := Coder{
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ToCode: make(map[rune]int, alphabetLen),
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ToRune: make(map[int]rune, alphabetLen),
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RuFreq: make(map[rune]float64, alphabetLen),
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}
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for i, r := range alphabet {
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coder.ToCode[r] = i
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coder.ToRune[i] = r
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coder.RuFreq[r] = alphabetFreq[i]
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}
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return coder
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}
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// Code with xor encoding.
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func (c Coder) Code(text, key []rune) []rune {
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res := make([]rune, 0, len(text))
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for i, r := range text {
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keyIndex := i % len(key)
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res = append(res, rune(c.ToRune[c.ToCode[r]^c.ToCode[key[keyIndex]]]))
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}
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return res
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}
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func (c Coder) RuneFrequency(text, key []rune) map[rune]int {
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res := make(map[rune]int, alphabetLen)
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for i, r := range text {
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keyIndex := i % len(key)
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res[rune(c.ToRune[c.ToCode[r]^c.ToCode[key[keyIndex]]])] += 1
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}
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return res
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}
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func (c Coder) AlphabetDivergence(analysis map[rune]int, textLen float64) float64 {
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var result float64
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for r, freq := range analysis {
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result += math.Abs(float64(freq)/textLen - c.RuFreq[r])
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}
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return result
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}
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