79 lines
2.0 KiB
Go
79 lines
2.0 KiB
Go
package main
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import "fmt"
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var d = [][]int{
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{0, 1, 2, 3, 4, 5, 6, 7, 8, 9},
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{1, 2, 3, 4, 0, 6, 7, 8, 9, 5},
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{2, 3, 4, 0, 1, 7, 8, 9, 5, 6},
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{3, 4, 0, 1, 2, 8, 9, 5, 6, 7},
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{4, 0, 1, 2, 3, 9, 5, 6, 7, 8},
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{5, 9, 8, 7, 6, 0, 4, 3, 2, 1},
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{6, 5, 9, 8, 7, 1, 0, 4, 3, 2},
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{7, 6, 5, 9, 8, 2, 1, 0, 4, 3},
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{8, 7, 6, 5, 9, 3, 2, 1, 0, 4},
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{9, 8, 7, 6, 5, 4, 3, 2, 1, 0},
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}
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var inv = []int{0, 4, 3, 2, 1, 5, 6, 7, 8, 9}
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var p = [][]int{
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{0, 1, 2, 3, 4, 5, 6, 7, 8, 9},
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{1, 5, 7, 6, 2, 8, 3, 0, 9, 4},
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{5, 8, 0, 3, 7, 9, 6, 1, 4, 2},
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{8, 9, 1, 6, 0, 4, 3, 5, 2, 7},
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{9, 4, 5, 3, 1, 2, 6, 8, 7, 0},
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{4, 2, 8, 6, 5, 7, 3, 9, 0, 1},
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{2, 7, 9, 3, 8, 0, 6, 4, 1, 5},
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{7, 0, 4, 6, 9, 1, 3, 2, 5, 8},
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}
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func verhoeff(s string, validate, table bool) interface{} {
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if table {
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t := "Check digit"
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if validate {
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t = "Validation"
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}
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fmt.Printf("%s calculations for '%s':\n\n", t, s)
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fmt.Println(" i nᵢ p[i,nᵢ] c")
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fmt.Println("------------------")
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}
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if !validate {
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s = s + "0"
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}
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c := 0
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le := len(s) - 1
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for i := le; i >= 0; i-- {
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ni := int(s[i] - 48)
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pi := p[(le-i)%8][ni]
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c = d[c][pi]
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if table {
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fmt.Printf("%2d %d %d %d\n", le-i, ni, pi, c)
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}
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}
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if table && !validate {
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fmt.Printf("\ninv[%d] = %d\n", c, inv[c])
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}
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if !validate {
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return inv[c]
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}
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return c == 0
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}
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func main() {
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ss := []string{"236", "12345", "123456789012"}
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ts := []bool{true, true, false, true}
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for i, s := range ss {
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c := verhoeff(s, false, ts[i]).(int)
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fmt.Printf("\nThe check digit for '%s' is '%d'\n\n", s, c)
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for _, sc := range []string{s + string(c+48), s + "9"} {
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v := verhoeff(sc, true, ts[i]).(bool)
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ans := "correct"
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if !v {
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ans = "incorrect"
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}
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fmt.Printf("\nThe validation for '%s' is %s\n\n", sc, ans)
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}
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}
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}
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