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/*

Redistribution and use in source and binary forms, with or without

modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright

    notice, this list of conditions and the following disclaimer.

    * Redistributions in binary form must reproduce the above copyright

    notice, this list of conditions and the following disclaimer in the

    documentation and/or other materials provided with the distribution.

    * Neither the name of "The Computer Language Benchmarks Game" nor the

    name of "The Computer Language Shootout Benchmarks" nor the names of

    its contributors may be used to endorse or promote products derived

    from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

POSSIBILITY OF SUCH DAMAGE.

*/

/* The Computer Language Benchmarks Game

 * http://shootout.alioth.debian.org/

 *

 * contributed by The Go Authors.

 */

package main

import (

        "flag"

        "fmt"

        "strconv"

)

const (

        blue = iota

        red

        yellow

        ncol

)

var complement = [...]int{

        red | red<<2:       red,

        red | yellow<<2:    blue,

        red | blue<<2:      yellow,

        yellow | red<<2:    blue,

        yellow | yellow<<2: yellow,

        yellow | blue<<2:   red,

        blue | red<<2:      yellow,

        blue | yellow<<2:   red,

        blue | blue<<2:     blue,

}

var colname = [...]string{

        blue:   "blue",

        red:    "red",

        yellow: "yellow",

}

// information about the current state of a creature.

type info struct {

        colour int // creature's current colour.

        name   int // creature's name.

}

// exclusive access data-structure kept inside meetingplace.

// if mate is nil, it indicates there's no creature currently waiting;

// otherwise the creature's info is stored in info, and

// it is waiting to receive its mate's information on the mate channel.

type rendez struct {

        n    int         // current number of encounters.

        mate chan<- info // creature waiting when non-nil.

        info info        // info about creature waiting.

}

// result sent by each creature at the end of processing.

type result struct {

        met  int

        same int

}

var n = 600

func main() {

        flag.Parse()

        if flag.NArg() > 0 {

                n, _ = strconv.Atoi(flag.Arg(0))

        }

        for c0 := 0; c0 < ncol; c0++ {

                for c1 := 0; c1 < ncol; c1++ {

                        fmt.Printf("%s + %s -> %s\n", colname[c0], colname[c1], colname[complement[c0|c1<<2]])

                }

        }

        fmt.Print("\n")

        pallmall([]int{blue, red, yellow})

        pallmall([]int{blue, red, yellow, red, yellow, blue, red, yellow, red, blue})

}

func pallmall(cols []int) {

        // invariant: meetingplace always contains a value unless a creature

        // is currently dealing with it (whereupon it must put it back).

        meetingplace := make(chan rendez, 1)

        meetingplace <- rendez{n: 0}

        ended := make(chan result)

        msg := ""

        for i, col := range cols {

                go creature(info{col, i}, meetingplace, ended)

                msg += " " + colname[col]

        }

        fmt.Println(msg)

        tot := 0

        // wait for all results

        for _ = range cols {

                result := <-ended

                tot += result.met

                fmt.Printf("%v%v\n", result.met, spell(result.same, true))

        }

        fmt.Printf("%v\n\n", spell(tot, true))

}

// in this function, variables ending in 0 refer to the local creature,

// variables ending in 1 to the creature we've met.

func creature(info0 info, meetingplace chan rendez, ended chan result) {

        c0 := make(chan info)

        met := 0

        same := 0

        for {

                var othername int

                // get access to rendez data and decide what to do.

                switch r := <-meetingplace; {

                case r.n >= n:

                        // if no more meetings left, then send our result data and exit.

                        meetingplace <- rendez{n: r.n}

                        ended <- result{met, same}

                        return

                case r.mate == nil:

                        // no creature waiting; wait for someone to meet us,

                        // get their info and send our info in reply.

                        meetingplace <- rendez{n: r.n, info: info0, mate: c0}

                        info1 := <-c0

                        othername = info1.name

                        info0.colour = complement[info0.colour|info1.colour<<2]

                default:

                        // another creature is waiting for us with its info;

                        // increment meeting count,

                        // send them our info in reply.

                        r.n++

                        meetingplace <- rendez{n: r.n, mate: nil}

                        r.mate <- info0

                        othername = r.info.name

                        info0.colour = complement[info0.colour|r.info.colour<<2]

                }

                if othername == info0.name {

                        same++

                }

                met++

        }

}

var digits = [...]string{"zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"}

func spell(n int, required bool) string {

        if n == 0 && !required {

                return ""

        }

        return spell(n/10, false) + " " + digits[n%10]

}