110 lines
2.4 KiB
Go
110 lines
2.4 KiB
Go
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package main
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import (
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"fmt"
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"sort"
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)
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const (
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INFINITY = 26
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)
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var debugSearch bool
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type DummyWriter struct {
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}
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func (d DummyWriter) Write(p []byte) (n int, err error) {
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n = len(p)
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return
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}
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func DebugSearch(input []rune) {
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debugSearch = true
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parsed := NewParser(input).Parse()
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generator := NewStdGenerator(DummyWriter{})
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generator.Generate(parsed)
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}
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func SearchPlates(plates map[float64]int, goalWeight float64) []float64 {
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if debugSearch {
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fmt.Println("searching", goalWeight)
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}
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root := &DFSNode{}
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root.remainingWeight = goalWeight
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root.residualPlates = make(map[float64]int)
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root.plate = -1
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for k, v := range plates {
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root.residualPlates[k] = v
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}
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optimum := root
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root.search(&optimum)
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usedPlates := optimum.usedPlates()
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if debugSearch {
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fmt.Println("found", usedPlates)
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}
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return usedPlates
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}
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type DFSNode struct {
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parent *DFSNode
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depth int
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remainingWeight float64
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plate float64
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residualPlates map[float64]int
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}
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func (parent *DFSNode) newChild(plate float64) *DFSNode {
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node := &DFSNode{}
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node.parent = parent
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node.depth = parent.depth + 1
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node.remainingWeight = parent.remainingWeight - plate*2
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node.plate = plate
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node.residualPlates = make(map[float64]int)
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for k, v := range parent.residualPlates {
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node.residualPlates[k] = v
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}
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node.residualPlates[plate] -= 2
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return node
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}
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func (n *DFSNode) usedPlates() (plates []float64) {
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for node := n; node != nil; node = node.parent {
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if node.plate > 0 {
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plates = append([]float64{node.plate}, plates...)
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}
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}
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return
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}
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func (n *DFSNode) successors() (children []*DFSNode) {
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keys := []float64{}
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for weight, amount := range n.residualPlates {
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if amount >= 2 && weight*2 <= n.remainingWeight && (n.plate == -1 || weight <= n.plate) && n.remainingWeight/weight <= INFINITY {
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keys = append(keys, weight)
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}
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}
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sort.Float64s(keys)
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for i := len(keys) - 1; i >= 0; i-- {
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children = append(children, n.newChild(keys[i]))
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}
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return
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}
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func (n *DFSNode) search(optimum **DFSNode) {
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successors := n.successors()
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if len(successors) == 0 {
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// leaf
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if n.remainingWeight < (*optimum).remainingWeight || (n.remainingWeight == (*optimum).remainingWeight && n.depth < (*optimum).depth) {
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*optimum = n
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if debugSearch {
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fmt.Printf("optimum: residual plates %v, remaining weight %v\n", (*optimum).residualPlates, (*optimum).remainingWeight)
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}
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}
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} else {
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for _, succ := range successors {
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succ.search(optimum)
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}
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}
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}
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