Fast, Cheap, and Good - Choose any Two

Question

As programmers, we all know the saying: "You can have it fast and good, but it won't be cheap, you can have it cheap and good, but it won't be fast, or you can have it fast and cheap, but it won't be good."

For this challenge, you are implementing an imaginary configuration tool for your custom programming services. You should render a set of three check boxes, with a heading of "SELECT ANY TWO":

SELECT ANY TWO  
☐ FAST  
☐ CHEAP  
☐ GOOD

Once two items have been selected, the third item must be disabled. Upon deselecting one of the two selected items, all options must again be enabled. Put another way, if zero or one items are selected, all are still enabled, but if two items are selected, the third must be disabled.

No special controls allowed. The check boxes should be the standard check box in your language of choice. For example, don't use a "CheckBoxList" control, if your language has one. I'm imagining most entries will be HTML/jQuery, but that is not a rule. This is code golf, looking for the shortest entry.

WINNERS SO FAR

I'll break it down into categories. There are some clear winners:

jQuery: nderscore, Mr. Tenacity Under 100b when you exclude text "resources". Honorable mention should also go to Matt for introducing the jQuery concepts that many took inspiration from.

Dyalog APL: marinus, a.k.a. Mr. Unicode How do you type all those things? I can see why you would want to write short programs.

PHP: SuperScript I believe this is the shortest entry that actually disables rather than deselecting the third option, following the strictest interpretation of the rules.

Answer 1

Javascript (ES5) with jQuery - 143 (Demo)

I modified Matt's solution and golfed it as far down as I think it can go:

$("*").html(["SELECT ANY TWO","FAST","GOOD","CHEAP"].join("<input type=checkbox onclick=(a=$('input:not(:checked)')).prop('disabled',!a[1])>"))

Javascript (ES5) without jQuery - 185 175 (Demo)

Using jQuery is kind of cheating, so here's a solution without it:

(d=document).write(["SELECT ANY TWO","FAST","GOOD","CHEAP"].join("<input type=checkbox onclick='for(b in a=d.querySelectorAll(\"input:not(:checked)\"))a[b].disabled=!a[1]'>"))

---

If we're allowed to prevent the user from checking the 3rd box instead of actually disabling the field, we can make it even shorter:

With jQuery - 126 123 (Demo)

$("*").html(["SELECT ANY TWO","FAST","GOOD","CHEAP"].join("<input type=checkbox onclick=this.checked*=!$(':checked')[2]>"))

Without jQuery - 150 147 (Demo)

(d=document).write(["SELECT ANY TWO","FAST","GOOD","CHEAP"].join("<input type=checkbox onclick=this.checked*=!d.querySelectorAll(':checked')[2]>"))

Answer 2

JavaScript - 184 169 (with jQuery)

b="input",a="<input type=checkbox>",c=":checked";$("body").html("SELECT ANY TWO"+a+"FAST"+a+"GOOD"+a+"CHEAP").click(function(){$(b).not(c).attr("disabled",!!$(b+c)[1])})

http://jsfiddle.net/L33JK/16/

EDIT: improved with help from @Daniel Lisik - https://codegolf.stackexchange.com/a/26805/16278

Answer 3

Dyalog APL (on Windows) (169)

This is a static function, to test it if you don't know APL, type )ed C and paste this in the edit window, then run C.

C
'R'⎕WC'Form' 'Select any two',2/⊂S←2/20
1 21 41{('R.',⊃⍵)⎕WC'Button'⍵(⍺1)S'Check'('Event' 'Select' 'F')}¨'Fast' 'Cheap' 'Good'
B←R.(F C G)
F←{B.Active←X∨2≠+/X←B.State}

Newer bits of APL have long keywords. I still beat HTML though.

Explanation:

• 'R'⎕WC'Form' 'Select any two',2/⊂S←2/20: create a form R, with title Select any two and size and position 20 20. Also stores 20 20 in S.
• 1 21 41{...}¨'Fast' 'Cheap' 'Good': for each of these pairs of data (name and y-coordinate, which are the only variables that differ between the checkboxes:
  • ('R.',⊃⍵)⎕WC'Button': create a button within R with the first letter of the name,
  • ⍵(⍺1)S'Check': with the right argument as the title, (left arg, 1) as position, reusing S as the size and Check as style,
  • ('Event' 'Select' 'F'), which calls the function F when clicked.
• B←R.(F C G): use B as an abbreviation for the three checkboxes we created
• F←{...}: define the callback function as:
  • X←B.State: get the state for each checkbox and store them in X,
  • X∨2≠+/X: sum X, if this is not equal to two all checkboxes must be active, if it is equal to two only checked checkboxes must be active
  • B.Active←: enable or disable the checkboxes

Result:

Answer 4

Python 3 2, 454 434 ... 393 392 bytes

I thought, Python must be shorter than Java. Here is the "proof" (EDIT: now it really is shorter):

from Tkinter import*
t=Tk()
r=str.replace
exec r(r(r(r('a@b@c@l=Label(t,text="SELECT ANY TWO");A`FAST|a);B`CHEAP|b);C`GOOD|c);l^A^B^C^','`','=Checkbutton(t,text="'),'|','",v='),'^','.pack();'),'@','=IntVar();')
def f(p,b,B,s):
 for i in 0,1,2:
    y=b[i].get()
    if p[i]-y:
     p[i]=y;s-=1
     if p[i]:s>0and B[i].toggle();s+=2
 t.after(1,f,p,b,B,s)
t.after(1,f,[0]*3,[a,b,c],[A,B,C],0)
t.mainloop()

For those of you curious as to what the exec expression actually executes, it executes this (this is what the replaces do to the string. Newlines added for readability):

a=IntVar();
b=IntVar();
c=IntVar();
l=Label(t,text="SELECT ANY TWO");
A=Checkbutton(t,text="FAST",v=a);
B=Checkbutton(t,text="CHEAP",v=b);
C=Checkbutton(t,text="GOOD",v=c);
l.pack();
A.pack();
B.pack();
C.pack();

This uses the same logic as my Java answer: unselect the checkbox if it causes more than 2 checkboxes to be selected. Unf Fortunately Unfortunately, I spent more less more bytes doing this.

EDITS:

1. massive adjustment of code to use exec, saving a whopping 1 byte!
2. switched to python 2 to squeeze two bytes from the exec (removing parentheses).
3. more golfing. Includes changing range(3) to 0,1,2 and changing the indentation to have one layer of tabs. Unsure if \t\t would work instead of \t__(_ is the space character). Finally reached the longest my Java answer ever was.
4. used replace trick
5. used Bakiru's suggestion, and golfed some more. Actually made it shorter than Java! But now, the Java answer got golfed more, so this is again longer. :-(
6. used improved replace trick.
7. changed a != for a -.

Answer 5

Java, 421 ... 369 351 bytes

import java.awt.*;class F extends Checkbox{F(String s){super(s);}public static void main(String[]a){new Frame(){{add(new Panel(){{add(new Label("SELECT ANY TWO"));F[]c={new F("FAST"),new F("CHEAP"),new F("GOOD")};for(F b:c){add(b);b.addItemListener(e->{int x=0;for(F d:c)x+=d.getState()?1:0;if(x>2)((F)e.getSource()).setState(1<0);});}}});}}.show();}}

Java... because Java. Nicer looking code:

import java.awt.*;

class F extends Checkbox {
    F(String s) {
        super(s);
    }

    public static void main(String[] a) {
        new Frame() {
            {
                add(new Panel() {
                    {
                        add(new Label("SELECT ANY TWO"));
                        F[] c = {new F("FAST"), new F("CHEAP"), new F("GOOD")};
                        for (F b: c) {
                            add(b);
                            b.addItemListener(e -> {
                                int x = 0;
                                for (F d: c) {
                                    x += d.getState() ? 1 : 0;
                                }
                                if (x > 2) ((F) e.getSource()).setState(1 < 0);
                            });
                        }
                    }
                });
            }
        }.show();
    }
}

Sample run (different sizings of the window, first is on startup):

The checkboxes are arranged horizontally; this is allowed. It would take much more to align it properly. Also, I'm disabling by unchecking the box when it is clicked, not by making it impossible to be clicked.

EDITS:

1. saved 3 bytes by making the main class extend Checkbox.
2. reread Lambda Expressions and realized that the type name was unnecessary. Take that Python!
3. converted a while loop to a foreach loop (thanks Lee); why didn't I think of that before?
4. saved 18 bytes by using an anonymous class and an instance initalizer for both the Frame and Panel.

Answer 6

Rebol, 219 197

load-gui p: func[p][p/state/value]x: func[v][if all[p a p b p c][set-face v false]] view [title"SELECT ANY TWO"a: check"FAST"on-action[x a]b: check"CHEAP"on-action[x b]c: check"GOOD"on-action[x c]]

Ungolfed:

load-gui    ;; this is temporary while r3-gui is in beta

p: func [p] [p/state/value]

x: func [v] [
    if all [p a p b p c] [set-face v false]
]

view [
    title "SELECT ANY TWO"
    a: check "FAST" on-action [x a]
    b: check "CHEAP" on-action [x b]
    c: check "GOOD" on-action [x c]
]

This is the Rebol 3 View dialect (r3-gui). Screendump below from Ubuntu Linux:

Update - Thanks to Earl & Graham from Rebol SO Chatroom for shaving 22 chars of the code - http://chat.stackoverflow.com/transcript/message/16345039#16345039

Answer 7

C++11/Qt5.2 - 561 481 433 423 369

Because why not.

Shockingly, as of now we are shorter than Python, and the non-buggy C#, and tied with Java!

Credits to EveBird for cutting it down from 561 to 481.

And once more EveBird shortens it from 481 to 433!

Took a few off with a lambda connect

Down to 389 with C++11 initializers

And 373 without the separate class

Removed a few spaces - 369

Golf'd:

#include<QtWidgets>
#define C(x,y,z)z.setEnabled(x.isChecked()+y.isChecked()<2);
#define S(x)l.addWidget(&x);
#define X(x)S(x);x.connect(&x,&QCheckBox::clicked,[&](){C(g,f,c)C(g,c,f)C(f,c,g)});
int main(int n,char**v){QApplication a(n,v);QWidget m;QLabel t{"Select any two"};QCheckBox g{"Good"},f{"Fast"},c{"Cheap"};QVBoxLayout l(&m);S(t)X(g)X(f)X(c)m.show();a.exec();}

Sort of Un-Golfed:

#include<QtWidgets>

#define C(x,y,z)z.setEnabled(x.isChecked()+y.isChecked()<2);
#define S(x)l.addWidget(&x);
#define X(x)S(x);connect(&x, &QCheckBox::clicked, [&](){C(g,f,c)C(g,c,f)C(f,c,g)});

int main(int n,char**v){ 
    QApplication a(n,v);
    QWidget m;
    QLabel t{"Select any two"};
    QCheckBox g{"Good"},f{"Fast"},c{"Cheap"};
    QVBoxLayout l(&m);
    S(t)X(g)X(f)X(c)m.show();
    a.exec();
}

Answer 8

CoffeeScript - 167, 154

CoffeeScript port of @Matt's answer.

b="input";a="<input type=checkbox>";c=":checked";$("body").html("SELECT ANY TWO#{a}FAST#{a}GOOD#{a}CHEAP").click ->$(b).not(c).attr "disabled",!!$(b+c)[1]

Somewhat ungolfed:

b = "input"
a = "<input type=checkbox>"
c = ":checked"

$( "body" ).html( "SELECT ANY TWO#{a}FAST#{a}GOOD#{a}CHEAP" ).click ->
    $( b ).not( c ).attr "disabled", !!$( b + c )[1]

JSFiddle.

Answer 9

Thanks to Rotem and Johnbot for the golfing help!

C# 343 334

This one uses the same "cheat" as Quincunx's Java answer - the checkboxes aren't actually disabled; they just don't allow you to check them if that check makes 3.

using System.Windows.Forms;using System.Linq;class P:Form{static void Main(){P p=new P();p.Text="SELECT ANY TWO";int y=0;var a=new CheckBox[3];foreach(var n in "FAST CHEAP GOOD".Split()){var c=new CheckBox();a[y]=c;c.Top=y++*50;c.Text=n;c.Validating+=(s,e)=>{if(a.Count(b=>b.Checked)>1)e.Cancel=true;};p.Controls.Add(c);}Application.Run(p);}}

There's also a minor bug that you can't close the window after selecting the third checkbox unless you unselect one, because the validation won't pass. But this is code-golf, so who cares? ;)

C# 403 397 374

This is a proper one that actually disables the third checkbox.

using System.Windows.Forms;using System.Linq;class P:CheckBox{static void Main(){var p=new Form{Text="SELECT ANY TWO"};P[]a=null;a="FAST CHEAP GOOD".Split().Select((x,i)=>{var c=new P{Top=i*50,Text=x};c.Click+=(s,e)=>{a.First(b=>!b.Checked).Enabled=a.Count(b=>b.Checked)>1?1<0:a.All(b=>b.Enabled=0<1);};p.Controls.Add(c);return c;}).ToArray();Application.Run(p);}}

Kinda ungolfed:

using System.Windows.Forms;
using System.Linq;

class P:Form
{
    static void Main()
    {
        P p = new P();
        p.Text = "SELECT ANY TWO";
        int y = 0;
        var a = new CheckBox[3];
        foreach (var n in "FAST CHEAP GOOD".Split())
        {
            var c = new CheckBox(); a[y] = c; c.Top = y++ * 50; c.Text = n; c.Click += (s, e) =>
            {
                if (a.Count(b => b.Checked) == 2)
                {
                    a.First(b => !b.Checked).Enabled = false;
                }
                else
                {
                    foreach (var b in a) b.Enabled = true;
                }
            };
            p.Controls.Add(c);
        }
        Application.Run(p);
    }
}

Answer 10

PHP, Javascript, jQuery - 135b

I was admiring @nderscore's answer, but then I decided to copy and one-up him.

<?echo"SELECT ANY TWO".($m="<input type=checkbox onclick=(a=$('input:not(:checked)')).prop('disabled',!a[1])>")."FAST$m GOOD$m CHEAP"?>

Basically I replaced his .join trick with some PHP Hypertext Preprocessing.

Answer 11

Ruby, 219 218 bytes

I use the same Tk widgets as the Python 3 answer by Quincunx.

This program breaks the rules because it has a check box list. (The rules said, "Don't use a check box list.") Yes, a is an array of 3 TkCheckButton objects, and I believe that an array is a list. My defense is that I did not use any existing check box list, but I used the standard check boxes and made my own list.

require'tk'
o=->(c){c.variable.value>?0}
TkLabel.new{text'SELECT ANY TWO'
pack}
a=%w[FAST CHEAP GOOD].map{|t|TkCheckButton.new{text t
command{a.map{|c|c.state a.count(&o)<2||o[c]?:normal: :disabled}}
pack}}
Tk.mainloop

I tested with Ruby 2.1.0 and Tk 8.5.15.

• o[c] is a predicate to test if check button c is selected. With the default strings, c.variable.value is '0' or '1', so the string comparison is only true if '1'>'0'. EDIT: I saved 1 byte (219 down to 218) by changing '0' to ?0. In Ruby, ?0 is a character constant.
• a.count(&o) uses the predicate to count the selected check buttons.
• When the user toggles a check button, the command calls a.map to loop for all buttons, making them :normal or :disabled.

Answer 12

AngularJS - 214

<input type=checkbox ng-model=fast ng-disabled=cheap&&good>FAST</input>
<input type=checkbox ng-model=cheap ng-disabled=fast&&good>CHEAP</input>
<input type=checkbox ng-model=good ng-disabled=fast&&cheap>GOOD</input>

Answer 13

Mathematica

A more code-golfed version as suggested by David, 255 characters:

h = Checkbox;
i = Dynamic;
j = Enabled;
t = True;
i[
 If[Total@Boole@{a, b, c} == 2,
  {d, e, f} = {a, b, c},
  {d, e, f} = {t, t, t}
  ];
 Row@{
   "SELECT ANY TWO",
   h[i@a, j -> d], "FAST",
   h[i@b, j -> e], "CHEAP",
   h[i@c, j -> f], "GOOD"
   }
 ]

Answer 14

JavaScript (with jQuery) - 224, 222, 210, 205, 178

a="<input type=checkbox>",c=":checked",e="input",f="disabled",d=$("body").html("SELECT ANY TWO"+a+" FAST"+a+"CHEAP"+a+"GOOD").click(function(){$(e).not(c).attr(f,$(e+c).length>1)})

Thanks to a comment from brilliant @Matt I reduced the code by 27 characters.

JSFiddle

Answer 15

mIRC script (727 719 bytes)

Forgot about this language until a drunken conversation last night.

alias select_two {
  dialog -m s2 s2
}

dialog s2 {
  title "Select any two:"
  size -1 -1 200 100
  check "Fast",1, 5 10 170 25
  check "Cheap",2, 5 30 170 25
  check "Good",3, 5 50 170 25 
}

on *:dialog:s2:sclick:*: {
  if ($did(s2, $did).state = 1) {
    if ($did = 1) {
      if ($did(s2, 2).state = 1) { did -b s2 3 }
      if ($did(s2, 3).state = 1) { did -b s2 2 }
    }
    if ($did = 2) {
      if ($did(s2, 1).state = 1) { did -b s2 3 }
      if ($did(s2, 3).state = 1) { did -b s2 1 }
    }
    if ($did = 3) {
      if ($did(s2, 1).state = 1) { did -b s2 2 }
      if ($did(s2, 2).state = 1) { did -b s2 1 }
    }
  }
  if ($did(s2, $did).state = 0) {
    did -e s2 1
    did -e s2 2
    did -e s2 3
  }
}

More should be coded in this language! But there needs to be a way to make this into a real mess so it can be as good as Perl.

Edit: noticed that my Python-isms are leaking through and was able to reduce the code by 8 bytes!

Answer 16

k3 - 95

a[`FAST`CHEAP`GOOD]:0
a[.;`c]:`check
a..l:"SELECT ANY TWO"
a..t:"if[3=+/a[];.[_v;_i;:;0]]"
`show$`a

code is here

_{(source: nsl.com)}

Answer 17

C#, 335 333 326 320 308

Based off Bobs Answer, mine does use fewer characters than his (335 v 342), but I might not understand fully how to count this.

using System.Linq;using System.Windows.Forms;class P:Form{static void Main(){new P();}P(){Text="SELECT ANY TWO";var a="FAST CHEAP GOOD".Split().Select(r=>new CheckBox{Text=r,Top=r[0]%9*20}).ToList();a.All(r=>{r.Validating+=(b,c)=>c.Cancel=a.Count(z=>z.Checked)>1;Controls.Add(r);return 1>0;});ShowDialog();}}

Ungolfed

using System.Linq;
using System.Windows.Forms;

class P : Form
{
    static void Main()
    {
        new P();
    }

    P()
    {
        Text = "SELECT ANY TWO";

        var a = "FAST CHEAP GOOD".Split().Select(r => new CheckBox
        {
            Text = r,
            Top = r[0] % 9 * 20
        }).ToList();

        //loops, I dont need no stinking loops
        a.All(r => { r.Validating += (b, c) => c.Cancel = a.Count(z => z.Checked) > 1; Controls.Add(r); return 1 > 0; });
        ShowDialog();
    }
}

Answer 18

Groovy - 357 221 217 chars

I've ported Quincunx's solution to Groovy 2.2.1, using SwingBuilder (and made it even more Groovier):

c=[];new groovy.swing.SwingBuilder().frame(){panel(){label("SELECT ANY TWO");f={if(c.count{it.isSelected()}>2)it.source.setSelected(1<0)};["FAST","CHEAP","GOOD"].each{c<<checkBox(label:it,itemStateChanged:f)}}}.show()

Ungolfed:

c=[]
new groovy.swing.SwingBuilder().frame() {
    panel() {
        label("SELECT ANY TWO")
        f = { if (c.count{it.isSelected()} > 2) it.source.setSelected(1<0) }
        ["FAST","CHEAP","GOOD"].each { c << checkBox(label: it, itemStateChanged: f) }
    }
}.show()

Answer 19

QML - 369 315 254 251 248 bytes

Here goes QML (QtQuick 2.0) version, given only the .qml file contents. This code requires Qt 5.1 at least to run. Not a big deal as its huge compared to other solutions (248 bytes), but it's a full featured cross-platform application (Android and iOs included)! :D

    import QtQuick 2.0;import QtQuick.Controls 1.1;Row{Text{text:"SELECT ANY TWO"}CheckBox{id:a;text:"FAST";enabled:!b.checked|!c.checked}CheckBox{id:b;text:"CHEAP";enabled:!a.checked|!c.checked}CheckBox{id:c;text:"GOOD";enabled:!b.checked|!a.checked}}

To run it, save the code to a .qml file, install Qt 5.1 and run qmlscene.exe (or just qmlscene on linux), which will show an open file dialog. Chose the .qml file you've saved the code to and see the awesome result! :D

Answer 20

JavaScript 209 (was 346)

Shortened: thanks for comments.

function f(){var a=document.getElementsByClassName("x"),n=0,i=0;for(i in a){if(a[i].checked)n++;}if(n<2){for(i in a){a[i].disabled=false;}}else{for(i in a){i(false===a[i].checked){a[i].disabled=true;break;}}}}

Golfed function:

function f(a,b,c){
var x=document.getElementById(a);
var y=document.getElementById(b);
var z=document.getElementById(c);
var n=0,i=0;
var a=[x,y,z];
for(i in a)
{
if(a[i].checked) n++;
}
if(n<2)
{
for(i in a)
{
a[i].disabled=false;
}
}
else
{
for(i in a)
{
if(false===a[i].checked)
{
a[i].disabled=true;
break;
}
}
}
}

HTML form: provides input and calls the function. * Form now uses class=x to group inputs.

<form>
        SELECT ANY TWO<br>
        FAST <input id="a" type="checkbox" class="x" value="0" onchange="f()"><br>
        CHEAP <input id="b" type="checkbox" class="x" value="1" onchange="f()"><br>
        GOOD <input id="c" type="checkbox" class="x" value="2" onchange="f()"><br>
    </form>

Tested with NetBeans and Chrome.

Answer 21

JavaScript / jQuery 237 234 229

Very similar approach as Matt's answer, although a little longer.

$(function(){var e="input ",t="disabled",n,r;$("body").html("SELECT ANY TWO|FAST|CHEAP|GOOD".replace(/\|/g,"<"+e+'type="checkbox">'));n=$(e);n.change(function(){n.removeAttr(t);r=$(":checked");if(r.length>1)n.not(r).attr(t,t)})})

Answer 22

Groovy

Based on the Java version, but much slimmed down ;)

Types were replaced by 'def', semicolons removed, add replaced by <<, the 1<0 replaced by 0, collect for creating the checkboxes, removed the itemevent type, removed casting the checkbox, enhanced the loops.

import java.awt.*
class F {
    def static main(a) {
        def f = new Frame()
        def p = new Panel()
        f << p
        p << new Label("SELECT ANY TWO")
        def c = ['FAST','CHECK','GOOD'].collect { new Checkbox(it) }
        c.each { b ->
            p << b
            b.addItemListener { e->
                int x = 0, i = 0
                3.times {
                    x += c[it].state ? 1 : 0
                }
                if (x > 2) {
                    e.source.state = 0                        
                }
            }
        }
        f.show()
    }
}

Answer 23

TCL 347

At least it beats Python and Java.

set d .
proc a v {upvar f f c c g g d d $v x
if $x&&$f+$c+$g==2 {set d .$f$c$g
$d configure -state disabled} 
if !$x {$d configure -state normal}}
set z -variable
set y -command
set x checkbutton
label .l -text {SELECT ANY TWO}
$x .011 -text FAST $z f $y a\ f
$x .101 -text CHEAP $z c $y a\ c
$x .110 -text GOOD $z g $y a\ g
pack .l .011 .101 .110

Note: if you start by selecting one checkbox and immediately unselecting it, you will get an error. You can fix it by adding 110 to the end of the first line.

Ungolfed:

# Keep track of the last disabled button. Set it to something valid to start with.
set last .110

proc toggled name {
        # Access some globals
        upvar fast  fast
        upvar cheap cheap
        upvar good  good
        upvar last  last
        upvar $name value

        # Just toggled one on, check if exactly two are now on
        if {$value == 1 && ($fast + $cheap + $good) == 2} {
                set last .$fast$cheap$good
                $last configure -state disabled
        }
        # Just toggled one off. Re-enable disabled one.
        if {$value == 0} {
                $last configure -state normal
        }
}

label .label -text {SELECT ANY TWO}

checkbutton .011 -text FAST  -variable fast  -command {toggled fast}
checkbutton .101 -text CHEAP -variable cheap -command {toggled cheap}
checkbutton .110 -text GOOD  -variable good  -command {toggled good}

pack .label .011 .101 .110

Answer 24

Javascript + Knockout: ~250 Characters

a=function(i){return "<input type=checkbox data-bind='value: "+i+", checked: x, disable: x().length>=2 && x().indexOf(\""+i+"\")==-1'>"},document.body.innerHTML = "SELECT ANY TWO"+a(0)+"Fast"+a(1)+"Good"+a(2)+"Cheap"; ko.applyBindings({x:ko.observableArray([])})

• Fiddle

Answer 25

AngularJS - 155 (Demo)

SELECT ANY TWO :<i ng-init=t=[]><p ng-repeat="(i,v) in ['FAST','CHEAP','GOOD']"><input type=checkbox ng-disabled=t[(i+1)%3]&&t[(i+2)%3] ng-model=t[i]>{{v}}

The ungolfed version:

SELECT ANY TWO :
<i ng-init="checkedArray = []" /> <!-- A useless tag to initialize the array (which can't be done on the `input` tag, unfortunately) -->
<p ng-repeat="(key, value) in ['FAST', 'CHEAP', 'GOOD']">
    <input
        type="checkbox"
        ng-model="checkedArray[key]"
        ng-disabled="checkedArray[(key + 1) % 3] && checkedArray[(key + 2) % 3]"
    />
    {{value}}
</p>

Answer 26

Ruby with Shoes, 133 characters

Shoes.app{para'SELECT ANY TWO'
$o=%w{FAST GOOD CHEAP}.map{|q|c=check{|c|$o[c]=!$o[c];$o.values.all?&&c.checked=p}
para q
[c,p]}.to_h}

Sample output:

Answer 27

FLTK, 303 characters

decl{int c;}Function{}{}{Fl_Window{}{xywh {9 9 195 195}}{Fl_Pack{}{label{SELECT ANY TWO}}{Fl_Check_Button{}{callback{e(o);}label FAST}Fl_Check_Button{}{callback{e(o);}label GOOD}Fl_Check_Button{}{callback{e(o);}label CHEAP}}}}Function{e(Fl_Button*o)}{}{code{if((c+=o->value()*2-1)>2){o->value(0);c--;}}}

Ungolfed:

decl { int c; }

Function {} {} {
    Fl_Window {} {
        xywh {9 9 195 195}
    } {
        Fl_Pack {} {
            label {SELECT ANY TWO}
        } {
            Fl_Check_Button {} {
                callback { e(o); }
                label FAST
            }
            Fl_Check_Button {} {
                callback { e(o); }
                label GOOD
            }
            Fl_Check_Button {} {
                callback { e(o); }
                label CHEAP
            }
        }
    }
}

Function { e(Fl_Button* o) } {} {
    code {
        if ((c += o->value() * 2 - 1) > 2) {
            o->value(0);
            c--;
        }
    }
}

Sample output: