34 lines
740 B
Go
34 lines
740 B
Go
package trinary
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import (
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"errors"
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"math/big"
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)
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// ParseTrinary takes a trinary string and returns the
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// decimal value
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func ParseTrinary(in string) (int64, error) {
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return convertNumStringBase(in, int64(3))
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}
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// convertNumStringBase takes a numeric string and the base of that string
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// and returns an int64 of the decimal representation
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func convertNumStringBase(in string, oldBase int64) (int64, error) {
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base := big.NewInt(oldBase)
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var sum big.Int
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for i := range in {
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x := big.NewInt(int64(in[i] - '0'))
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pow := big.NewInt(int64(len(in) - i - 1))
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var n big.Int
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n.Exp(base, pow, nil)
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n.Mul(x, &n)
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sum.Add(&sum, &n)
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if sum.Int64() < 0 {
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return 0, errors.New("Integer Overflow")
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}
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}
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return sum.Int64(), nil
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}
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