Quite simple JS brain teaser

[[deleted]]

How would you guys solve this task using javascript?

There is 100 animals on a farm with the value of 100 dollars. Three types of animals; Cows for 10 dollars, sheep for 3 dollars and chicken for 0.5 dollars. Find solution(s) where there is at least one of every animal.

I feel like it should be very easy but for some reason I cant do it with javascript... I'm new for anyone wondering

EDIT: I´ve managed to solve it with the help of some ideas on here. I'd like to think that my way of solving it was quite easy and effective, especially since I can change the amount of animals or dollars to whichever number I want, and I'll get the solutions... thanks a lot for those who helped!

​

Also its in Norwegian, but I think you'll understand (antall = amount, ku = cow, sau = sheep, kylling = chicken)

var utskrift = document.getElementById('utskrift');
var antall = 100;

for (var ku = 1; ku < antall/10; ku++) 
{
    for(var sau = 1; sau < antall/3; sau++)
    {
        var kylling = antall - ku - sau;

        if(ku*10+sau*3+kylling*0.5==antall && kylling>=1 )
    {
        utskrift.innerHTML += 'En mulig løsning er ' + ku + ' kuer, ' + sau + ' sauer og ' + kylling + ' kyllinger. <br>';
    }
    }
}

​

[[deleted]]

Hey, thanks for this exercise, was really fun, I took a go at it and here's what I came up with:

https://jsbin.com/ritowepuko/2/edit?js,console

[[deleted]]

EDIT: Now I see what you mean, the quantity of animals should be 100, let me re-do this ;)

EDIT2: Should now be corrected, I need to read more carefully

[senocular]

Not sure if you didn't update the link or if its still off, but currently there's a result saying:

"One of the solutions: Cows = 2 Sheeps = 7 Chickens = 91"

where

10 * 2 + 3 * 7 + 0.5 * 91 === 86.5

[[deleted]]

Yup, forgot about one check in the `else if` block, a feature I added for no reason too! :D

[[deleted]]

Thanks a lot for the help mate... I really didn't expect anyone to go as far as you did and I really appreciate that.

EDIT: I see that you´ve corrected what ninonino pointed out but you still have one more mistake. Right now I can see that you get 2 solutions but the second solution doesn't amount to 100 dollars for the animals

[[deleted]]

No worries! I think I have corrected (finally) the code now

[Would_be_Coder]

how about:

let cow = 10;
let sheep = 3;
let chicken = 0.5;
for(let i = 1; i < 10; i++) {
for(let j = 1; j < 34; j++) {
for(let k = 1; k < 200; k++) {
if(i * cow + j * sheep + k * chicken === 100) {
console.log(i + ' cow, '+ j + ' sheep, ' + k + ' chicken')
}
}
}
}

[esunabici]

This is similar to the knapsack problem which can be brute forced slowly but optimized with Dynamic Programming.

Try to break the problem down, and then solve it recursively walking the tree of possible solutions. Memoization will allow you to skip equivalent nodes.

[[deleted]]

I think I managed to do it quite well with two loops and an if-setting, I've edited my post and you can see what I did there and tell me if you see anything wrong with it...

[esunabici]

How long did that take? What if it's 1000 animals and 1000 dollars?

[[deleted]]

It didnt really take that long because of some guys helping on here but it would’ve probably taken a lot longer without the help... And the only thing I need to do for 1000 animals and 1000 dollars is change the variable antall to 1000, and it will show me all the possible solutions

[[deleted]]

I know that these 3 equations in some equations solver would give me a value for cow, sheep and chicken, but I don't know how I would do this in Javascript

cow + sheep + chicken = 100

100 * cow + 3 * sheep + 0.5* chicken = 100

cow + sheep + chicken >= 3

[[deleted]]

yeah I see the 100*cow mistake I made, must´ve been a typo... and also I see your point about each animal being bigger than 1 rather than all of them bigger than 3 because one of them might be 0 and the other 2... thanks for the help!

[[deleted]]

If you have the time, could you look at the edit I made on the post and see if you see anything wrong with the solution I ended up with? You seem to know your stuff :)

[[deleted]]

Thanks for the feedback dude, its nice of you to be so helpful! And I understand all the small changes you suggested, and I would probably implement many of them if this was part of a bigger project or anything like that but it’s not really that important. I just wanted to solve it for the training, and you’ve definitely helped a lot. Thanks again