40 lines
921 B
Plaintext
40 lines
921 B
Plaintext
func rangeFormat(a) {
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if a.Length() == 0 {
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return ""
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}
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var parts = []
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var n1 = 0
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while true {
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var n2 = n1 + 1
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while n2 < a.Length() && a[n2] == a[n2-1]+1 {
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n2 += 1
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}
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var s = a[n1].ToString()
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if n2 == n1+2 {
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s += "," + a[n2-1]
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} else if n2 > n1+2 {
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s += "-" + a[n2-1]
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}
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parts.Add(s)
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if n2 == a.Length() {
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break
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}
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if a[n2] == a[n2-1] {
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throw "Sequence repeats value \(a[n2])"
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}
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if a[n2] < a[n2-1] {
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throw "Sequence not ordered: \(a[n2]) < \(a[n2-1])"
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}
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n1 = n2
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}
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return String.Join(values: parts)
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}
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var rf = rangeFormat([
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0, 1, 2, 4, 6, 7, 8, 11, 12, 14,
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15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
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25, 27, 28, 29, 30, 31, 32, 33, 35, 36,
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37, 38, 39
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])
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print("range format: \(rf)")
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