Combinations in javascript

Question

Write a javascript program to distribute n identical objects among the r persons.

 

Example: n=2 identical objects.

 and r=2 , persons

so output would be like {1,1}{0,2} {2,0} 

 

function distribute(n,r){

} 

 

 

and one more problem I have

 

Write a javascript function to decrypt the letters in alphabet

for Example : input : nrfzh i.e. n : n +3=q, r:r+3=u and so on.

Output: 'quick'

function decrypt(input){

}

 

 Please help.

Thanks in Advance.