Task: Stable marriage problem




Go: package main

import "fmt"







type proposers map[string][]string
    
var mPref = proposers{
    "abe": []string{
        "abi", "eve", "cath", "ivy", "jan",
        "dee", "fay", "bea", "hope", "gay"},
    "bob": []string{
        "cath", "hope", "abi", "dee", "eve",
        "fay", "bea", "jan", "ivy", "gay"},
    "col": []string{
        "hope", "eve", "abi", "dee", "bea",
        "fay", "ivy", "gay", "cath", "jan"},
    "dan": []string{
        "ivy", "fay", "dee", "gay", "hope",
        "eve", "jan", "bea", "cath", "abi"},
    "ed": []string{
        "jan", "dee", "bea", "cath", "fay",
        "eve", "abi", "ivy", "hope", "gay"},
    "fred": []string{
        "bea", "abi", "dee", "gay", "eve",
        "ivy", "cath", "jan", "hope", "fay"},
    "gav": []string{
        "gay", "eve", "ivy", "bea", "cath",
        "abi", "dee", "hope", "jan", "fay"},
    "hal": []string{
        "abi", "eve", "hope", "fay", "ivy",
        "cath", "jan", "bea", "gay", "dee"},
    "ian": []string{
        "hope", "cath", "dee", "gay", "bea",
        "abi", "fay", "ivy", "jan", "eve"},
    "jon": []string{
        "abi", "fay", "jan", "gay", "eve",
        "bea", "dee", "cath", "ivy", "hope"},
}

type recipients map[string]map[string]int

var wPref = recipients{
    "abi": map[string]int{
        "bob": 1, "fred": 2, "jon": 3, "gav": 4, "ian": 5,
        "abe": 6, "dan": 7, "ed": 8, "col": 9, "hal": 10},
    "bea": map[string]int{
        "bob": 1, "abe": 2, "col": 3, "fred": 4, "gav": 5,
        "dan": 6, "ian": 7, "ed": 8, "jon": 9, "hal": 10},
    "cath": map[string]int{
        "fred": 1, "bob": 2, "ed": 3, "gav": 4, "hal": 5,
        "col": 6, "ian": 7, "abe": 8, "dan": 9, "jon": 10},
    "dee": map[string]int{
        "fred": 1, "jon": 2, "col": 3, "abe": 4, "ian": 5,
        "hal": 6, "gav": 7, "dan": 8, "bob": 9, "ed": 10},
    "eve": map[string]int{
        "jon": 1, "hal": 2, "fred": 3, "dan": 4, "abe": 5,
        "gav": 6, "col": 7, "ed": 8, "ian": 9, "bob": 10},
    "fay": map[string]int{
        "bob": 1, "abe": 2, "ed": 3, "ian": 4, "jon": 5,
        "dan": 6, "fred": 7, "gav": 8, "col": 9, "hal": 10},
    "gay": map[string]int{
        "jon": 1, "gav": 2, "hal": 3, "fred": 4, "bob": 5,
        "abe": 6, "col": 7, "ed": 8, "dan": 9, "ian": 10},
    "hope": map[string]int{
        "gav": 1, "jon": 2, "bob": 3, "abe": 4, "ian": 5,
        "dan": 6, "hal": 7, "ed": 8, "col": 9, "fred": 10},
    "ivy": map[string]int{
        "ian": 1, "col": 2, "hal": 3, "gav": 4, "fred": 5,
        "bob": 6, "abe": 7, "ed": 8, "jon": 9, "dan": 10},
    "jan": map[string]int{
        "ed": 1, "hal": 2, "gav": 3, "abe": 4, "bob": 5,
        "jon": 6, "col": 7, "ian": 8, "fred": 9, "dan": 10},
}

func main() {
    
    ps := pair(mPref, wPref)
    
    fmt.Println("\nresult:")
    if !validateStable(ps, mPref, wPref) {
        return 
    }
    
    for {
        i := 0 
        var w2, m2 [2]string
        for w, m := range ps {
            w2[i] = w
            m2[i] = m
            if i == 1 {
                break
            }
            i++
        }
        fmt.Println("\nexchanging partners of", m2[0], "and", m2[1])
        ps[w2[0]] = m2[1]
        ps[w2[1]] = m2[0] 
        
        if !validateStable(ps, mPref, wPref) {
            return
        }
        
    }
}   

type parings map[string]string 
    

func pair(pPref proposers, rPref recipients) parings {
    
    pFree := proposers{}
    for k, v := range pPref {
        pFree[k] = append([]string{}, v...)
    }
    rFree := recipients{}
    for k, v := range rPref {
        rFree[k] = v
    }
    
    
    type save struct {
        proposer string
        pPref    []string
        rPref    map[string]int
    }
    proposals := map[string]save{} 

    
    
    for len(pFree) > 0 { 
        var proposer string
        var ppref []string
        for proposer, ppref = range pFree {
            break 
        }
        if len(ppref) == 0 {
            continue 
        }
        
        recipient := ppref[0] 
        ppref = ppref[1:]     
        var rpref map[string]int
        var ok bool
        
        if rpref, ok = rFree[recipient]; ok {
            
            
        } else {
            
            s := proposals[recipient] 
            
            if s.rPref[proposer] < s.rPref[s.proposer] {
                fmt.Println("engagement broken:", recipient, s.proposer)
                
                pFree[s.proposer] = s.pPref 
                
                rpref = s.rPref
                
            } else {
                
                pFree[proposer] = ppref 
                continue
            } 
        }
        fmt.Println("engagement:", recipient, proposer)
        proposals[recipient] = save{proposer, ppref, rpref}
        delete(pFree, proposer)
        delete(rFree, recipient)
    }
    
    ps := parings{}
    for recipient, s := range proposals {
        ps[recipient] = s.proposer
    }
    return ps
}

func validateStable(ps parings, pPref proposers, rPref recipients) bool {
    for r, p := range ps {
        fmt.Println(r, p)
    }
    for r, p := range ps {
        for _, rp := range pPref[p] {
            if rp == r {
                break
            }
            rprefs := rPref[rp]
            if rprefs[p] < rprefs[ps[rp]] {
                fmt.Println("unstable.")
                fmt.Printf("%s and %s would prefer each other over"+
                    " their current pairings.\n", p, rp)
                return false
            }
        }
    }
    fmt.Println("stable.")
    return true
}








Ada: package Preferences
is

   type Guy_X is (no_guy, abe, bob, col, dan, ed, fred, gav, hal, ian, jon);
   subtype Guy is Guy_X range Guy_X'Succ(Guy_X'First) .. Guy_X'Last;

   type Girl_X is (no_girl, abi, bea, cath, dee, eve, fay, gay, hope, ivy, jan);
   subtype Girl is Girl_X range Girl_X'Succ(Girl_X'First) .. Girl_X'Last;

   type Extended_Rank is range 0 .. 10;
   subtype Rank is Extended_Rank range 1 .. Extended_Rank'Last;

   type His_Rank is array (Rank) of Girl;
   type He_Prefers is array (Guy) of His_Rank;

   Guys_Like : constant He_Prefers := He_Prefers'(
     abe  => His_Rank'(abi, eve, cath, ivy, jan, dee, fay, bea, hope, gay),
     bob  => His_Rank'(cath, hope, abi, dee, eve, fay, bea, jan, ivy, gay),
     col  => His_Rank'(hope, eve, abi, dee, bea, fay, ivy, gay, cath, jan),
     dan  => His_Rank'(ivy, fay, dee, gay, hope, eve, jan, bea, cath, abi),
     ed   => His_Rank'(jan, dee, bea, cath, fay, eve, abi, ivy, hope, gay),
     fred => His_Rank'(bea, abi, dee, gay, eve, ivy, cath, jan, hope, fay),
     gav  => His_Rank'(gay, eve, ivy, bea, cath, abi, dee, hope, jan, fay),
     hal  => His_Rank'(abi, eve, hope, fay, ivy, cath, jan, bea, gay, dee),
     ian  => His_Rank'(hope, cath, dee, gay, bea, abi, fay, ivy, jan, eve),
     jon  => His_Rank'(abi, fay, jan, gay, eve, bea, dee, cath, ivy, hope));

   type Her_Rank is array(Rank) of Guy;
   type She_Prefers is array (Girl) of Her_Rank;

   Girls_Like : constant She_Prefers := She_Prefers'(
     abi  => Her_Rank'(bob, fred, jon, gav, ian, abe, dan, ed, col, hal),
     bea  => Her_Rank'(bob, abe, col, fred, gav, dan, ian, ed, jon, hal),
     cath => Her_Rank'(fred, bob, ed, gav, hal, col, ian, abe, dan, jon),
     dee  => Her_Rank'(fred, jon, col, abe, ian, hal, gav, dan, bob, ed),
     eve  => Her_Rank'(jon, hal, fred, dan, abe, gav, col, ed, ian, bob),
     fay  => Her_Rank'(bob, abe, ed, ian, jon, dan, fred, gav, col, hal),
     gay  => Her_Rank'(jon, gav, hal, fred, bob, abe, col, ed, dan, ian),
     hope => Her_Rank'(gav, jon, bob, abe, ian, dan, hal, ed, col, fred),
     ivy  => Her_Rank'(ian, col, hal, gav, fred, bob, abe, ed, jon, dan),
     jan  => Her_Rank'(ed, hal, gav, abe, bob, jon, col, ian, fred, dan));

end Preferences;