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build.go
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build.go
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// Copyright (C) 2016 Mikael Berthe <mikael@lilotux.net>. All rights reserved.
// Use of this source code is governed by the MIT license,
// which can be found in the LICENSE file.
package takuzu
// This file contains the functions and methods used to build a new takuzu
// puzzle.
import (
"fmt"
"log"
"math/rand"
"time"
"github.com/pkg/errors"
)
func init() {
rand.Seed(time.Now().UTC().UnixNano())
}
type buildTakuzuOptions struct {
size int
minRatio, maxRatio int
simple bool
buildBoardTimeout, reduceBoardTimeout time.Duration
}
// ReduceBoard randomly removes as many numbers as possible from the
// takuzu board and returns a pointer to the new board.
// The initial takuzu might be modified.
func (tak Takuzu) ReduceBoard(trivial bool, wid string, buildBoardTimeout, reduceBoardTimeout time.Duration) (*Takuzu, error) {
size := tak.Size
// First check if the board is correct
if verbosity > 0 {
log.Printf("[%v]ReduceBoard: Checking for all grid solutions...", wid)
}
allSol := &[]Takuzu{}
_, err := tak.Clone().TrySolveRecurse(allSol, buildBoardTimeout)
ns := len(*allSol)
if err != nil && errors.Cause(err).Error() == "timeout" {
if verbosity > 0 {
log.Printf("[%v]ReduceBoard: There was a timeout (%d resolution(s) found).", wid, ns)
}
if ns == 0 {
return nil, err
}
//if ns < 10 { return nil, err }
if verbosity > 0 {
log.Printf("[%v]ReduceBoard: Going on anyway...", wid)
}
}
if verbosity > 0 {
log.Printf("[%v]ReduceBoard: %d solution(s) found.", wid, ns)
}
if ns == 0 {
return nil, err
} else if ns > 1 {
tak = (*allSol)[rand.Intn(ns)]
if verbosity > 0 {
log.Printf("[%v]ReduceBoard: Warning: there are %d solutions.", wid, ns)
log.Printf("[%v]ReduceBoard: Picking one randomly.", wid)
if verbosity > 1 {
tak.DumpBoard()
fmt.Println()
}
}
allSol = nil
} else {
// 1 and only 1 solution
if verbosity > 1 {
tak.DumpBoard()
fmt.Println()
}
}
if verbosity > 0 {
log.Printf("[%v]ReduceBoard: Grid reduction...", wid)
}
fields := make([]*Cell, size*size)
n := 0
for l := range tak.Board {
for c := range tak.Board[l] {
if tak.Board[l][c].Defined {
fields[n] = &tak.Board[l][c]
n++
}
}
}
nDigits := 0
initialDigits := n
ratio := 0
if verbosity > 0 {
log.Printf("[%v]ReduceBoard: %d%%", wid, ratio)
}
for ; n > 0; n-- {
var rollback bool
i := rand.Intn(n)
fields[i].Defined = false
if trivial {
full, err := tak.Clone().TrySolveTrivial()
if err != nil || !full {
rollback = true
}
} else {
allSol = &[]Takuzu{}
_, err := tak.Clone().TrySolveRecurse(allSol, reduceBoardTimeout)
if err != nil || len(*allSol) != 1 {
rollback = true
}
}
if rollback {
if verbosity > 1 {
log.Printf("[%v]ReduceBoard: Backing out", wid)
}
fields[i].Defined = true // Back out!
nDigits++
}
fields = append(fields[:i], fields[i+1:]...)
if verbosity > 0 {
nr := (initialDigits - n) * 100 / initialDigits
if nr > ratio {
ratio = nr
log.Printf("[%v]ReduceBoard: %d%%", wid, ratio)
}
}
}
if verbosity > 0 {
log.Printf("[%v]ReduceBoard: I have left %d digits.", wid, nDigits)
}
return &tak, nil
}
// newRandomTakuzu creates a new Takuzu board with a given size
// It is intended to be called by NewRandomTakuzu only.
func newRandomTakuzu(wid string, buildOpts buildTakuzuOptions) (*Takuzu, error) {
size := buildOpts.size
easy := buildOpts.simple
buildBoardTimeout := buildOpts.buildBoardTimeout
reduceBoardTimeout := buildOpts.reduceBoardTimeout
minRatio := buildOpts.minRatio
maxRatio := buildOpts.maxRatio
tak := New(size)
n := size * size
fields := make([]*Cell, n)
i := 0
for l := range tak.Board {
for c := range tak.Board[l] {
fields[i] = &tak.Board[l][c]
i++
}
}
if verbosity > 0 {
log.Printf("[%v]NewRandomTakuzu: Filling new board (%dx%[2]d)...", wid, size)
}
nop := 0
// #1. Loop until the ratio of empty cells is less than minRatio% (e.g. 55%)
for n > size*size*minRatio/100 {
i := rand.Intn(n)
fields[i].Defined = true
fields[i].Value = rand.Intn(2)
var err error
if _, err = tak.Validate(); err != nil {
if verbosity > 1 {
log.Printf("[%v]NewRandomTakuzu: Could not set cell value to %v", wid, fields[i].Value)
}
} else if _, err = tak.Clone().TrySolveTrivial(); err != nil {
if verbosity > 1 {
log.Printf("[%v]NewRandomTakuzu: Trivial checks: Could not set cell value to %v", wid, fields[i].Value)
}
}
if err == nil {
fields = append(fields[:i], fields[i+1:]...)
n--
continue
}
// If any of the above checks fails, we roll back
fields[i].Defined = false
fields[i].Value = 0 // Let's reset but it is useless
// Safety check to avoid deadlock on bad boards
nop++
if nop > 2*size*size {
log.Printf("[%v]NewRandomTakuzu: Could not fill up board!", wid)
// Givin up on this board
return nil, errors.New("could not fill up board") // Try again
}
}
var ptak *Takuzu
var removed int
// #2. Try to solve the current board; try to remove some cells if it fails
// Initial empty cells count
iecc := n
for {
// Current count of empty (i.e. undefined) cells
ec := iecc + removed
ecpc := ec * 100 / (size * size)
if verbosity > 0 {
log.Printf("[%v]NewRandomTakuzu: Empty cells: %d (%d%%)", wid, ec, ecpc)
}
if ecpc > maxRatio {
if verbosity > 0 {
log.Printf("[%v]NewRandomTakuzu: Too many empty cells (%d); giving up on this board", wid, ec)
}
break
}
var err error
ptak, err = tak.ReduceBoard(easy, wid, buildBoardTimeout, reduceBoardTimeout)
if err != nil && errors.Cause(err).Error() == "timeout" {
break
}
if err == nil && ptak != nil {
break
}
if verbosity > 0 {
log.Printf("[%v]NewRandomTakuzu: Could not use this grid", wid)
}
inc := size * size / 150
if inc == 0 {
inc = 1
}
tak.removeRandomCell(inc)
removed += inc
if verbosity > 1 {
log.Printf("[%v]NewRandomTakuzu: Removed %d numbers", wid, removed)
if verbosity > 1 {
tak.DumpBoard()
}
}
}
if ptak == nil {
if verbosity > 0 {
log.Printf("[%v]NewRandomTakuzu: Couldn't use this board, restarting from scratch...", wid)
}
return nil, errors.New("could not use current board") // Try again
}
return ptak, nil
}
// NewRandomTakuzu creates a new Takuzu board with a given size
func NewRandomTakuzu(size int, simple bool, wid string, buildBoardTimeout, reduceBoardTimeout time.Duration, minRatio, maxRatio int) (*Takuzu, error) {
if size%2 != 0 {
return nil, errors.New("board size should be an even value")
}
if size < 4 {
return nil, errors.New("board size is too small")
}
// minRatio : percentage (1-100) of empty cells when creating a new board
// If the board is wrong the cells will be removed until we reach maxRatio
if minRatio < 40 {
minRatio = 40
}
if minRatio > maxRatio {
return nil, errors.New("minRatio/maxRatio incorrect")
}
if maxRatio > 99 {
maxRatio = 99
}
buildOptions := buildTakuzuOptions{
size: size,
minRatio: minRatio,
maxRatio: maxRatio,
simple: simple,
buildBoardTimeout: buildBoardTimeout,
reduceBoardTimeout: reduceBoardTimeout,
}
var takP *Takuzu
for {
var err error
takP, err = newRandomTakuzu(wid, buildOptions)
if err == nil {
break
}
}
return takP, nil
}
func (tak Takuzu) removeRandomCell(number int) {
size := tak.Size
fields := make([]*Cell, size*size)
n := 0
for l := range tak.Board {
for c := range tak.Board[l] {
if tak.Board[l][c].Defined {
fields[n] = &tak.Board[l][c]
n++
}
}
}
for i := 0; i < number; i++ {
if n == 0 {
return
}
fields[rand.Intn(n)].Defined = false
fields = append(fields[:i], fields[i+1:]...)
n--
}
}