80 lines
1.5 KiB
Go
80 lines
1.5 KiB
Go
package main
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import (
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"fmt"
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"math"
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"strings"
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)
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func main() {
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for _, n := range [...]int64{
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0, 4, 6, 11, 13, 75, 100, 337, -164,
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math.MaxInt64,
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} {
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fmt.Println(fourIsMagic(n))
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}
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}
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func fourIsMagic(n int64) string {
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s := say(n)
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s = strings.ToUpper(s[:1]) + s[1:]
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t := s
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for n != 4 {
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n = int64(len(s))
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s = say(n)
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t += " is " + s + ", " + s
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}
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t += " is magic."
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return t
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}
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// Following is from https://rosettacode.org/wiki/Number_names#Go
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var small = [...]string{"zero", "one", "two", "three", "four", "five", "six",
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"seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen",
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"fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen"}
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var tens = [...]string{"", "", "twenty", "thirty", "forty",
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"fifty", "sixty", "seventy", "eighty", "ninety"}
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var illions = [...]string{"", " thousand", " million", " billion",
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" trillion", " quadrillion", " quintillion"}
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func say(n int64) string {
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var t string
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if n < 0 {
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t = "negative "
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// Note, for math.MinInt64 this leaves n negative.
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n = -n
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}
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switch {
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case n < 20:
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t += small[n]
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case n < 100:
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t += tens[n/10]
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s := n % 10
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if s > 0 {
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t += "-" + small[s]
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}
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case n < 1000:
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t += small[n/100] + " hundred"
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s := n % 100
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if s > 0 {
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t += " " + say(s)
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}
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default:
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// work right-to-left
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sx := ""
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for i := 0; n > 0; i++ {
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p := n % 1000
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n /= 1000
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if p > 0 {
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ix := say(p) + illions[i]
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if sx != "" {
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ix += " " + sx
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}
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sx = ix
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}
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}
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t += sx
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}
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return t
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}
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