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// Package alg provides base types for addition chain and addition sequence search algorithms.
package alg
import (
"math/big"
"github.com/mmcloughlin/addchain"
)
// ChainAlgorithm is a method of generating an addition chain for a target integer.
type ChainAlgorithm interface {
// FindChain generates an addition chain ending at target.
FindChain(target *big.Int) (addchain.Chain, error)
// String returns a name for the algorithm.
String() string
}
// SequenceAlgorithm is a method of generating an addition sequence for a set of
// target values.
type SequenceAlgorithm interface {
// FindSequence generates an addition chain containing every element of targets.
FindSequence(targets []*big.Int) (addchain.Chain, error)
// String returns a name for the algorithm.
String() string
}
// AsChainAlgorithm adapts a sequence algorithm to a chain algorithm. The
// resulting algorithm calls the sequence algorithm with a singleton list
// containing the target.
func AsChainAlgorithm(s SequenceAlgorithm) ChainAlgorithm {
return asChainAlgorithm{s}
}
type asChainAlgorithm struct {
SequenceAlgorithm
}
// FindChain calls FindSequence with a singleton list containing the target.
func (a asChainAlgorithm) FindChain(target *big.Int) (addchain.Chain, error) {
return a.FindSequence([]*big.Int{target})
}
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