46 lines
977 B
Go
46 lines
977 B
Go
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package cryptosquare
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import (
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"math"
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"regexp"
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"strings"
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)
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// TestVersion is an exercism thing
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const TestVersion = 1
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// Encode implements the classic method for composing
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// secret messages called a square code
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func Encode(txt string) string {
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r := regexp.MustCompile("[^a-zA-Z0-9]+")
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nrm := strings.ToLower(r.ReplaceAllString(txt, ""))
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// The string should be normalized now (alphanumeric, lower case)
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sqrt := int(math.Ceil(math.Sqrt(float64(len(nrm)))))
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var square, ret []string
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var tmp string
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// Build the initial square
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for i := 0; i < len(nrm); i++ {
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if i%sqrt == 0 && len(tmp) != 0 {
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square = append(square, tmp)
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tmp = ""
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}
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tmp += string(nrm[i])
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}
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square = append(square, tmp)
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tmp = ""
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// Now rebuild the string by columns
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for i := 0; i < len(square[0]); i++ {
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for j := 0; j < len(square); j++ {
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if i < len(square[j]) {
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tmp += string(square[j][i])
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}
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}
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ret = append(ret, tmp)
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tmp = ""
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}
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return strings.Join(ret, " ")
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}
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