No Repeats Please*

JavaScript
1

Tell us what’s happening:
I want to swap the element of the str, then I want to get every combination by adding +1 to every index of every element. How can I do that.
Your code so far


function permAlone(str) {
let splittedStr=str.split("")
let lengthOfSplittedStr=splittedStr.length;
let groupfGroups=[];
//console.log(lengthOfSplittedStr)
let factorial=1; 
for(let i=1;i<=lengthOfSplittedStr;i++){
        factorial*=i
}
for(let i =1;i<=factorial;i++){
        groupfGroups.push(splittedStr.slice(i,i))

}
console.log(groupfGroups)
}

permAlone('ab');

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Challenge: No Repeats Please

Link to the challenge:

2

Search about permutation algorithms.

When you will be able to permute an array, check for repeatning characters.

Tip: do not store all permutations. Try to permute and check on the fly.

2 Likes
3

I have done it, but I have used this link: https://www.30secondsofcode.org/js/s/permutations. I did not know how to permutate the string :frowning:

function permAlone(str) {

const splittedStr=str.split("")
const arrayOfArrays=[]
const globalRegex = new RegExp('(aa)+|(bb)+|(cc)+|(dd)+|(ee)+|(ff)+|(gg)+|(hh)+|(ii)+|(jj)+|(kk)+|(ll)+|(mm)+|(nn)+|(oo)+|(pp)+|(qq)+|(rr)+|(ss)+|(tt)+|(uu)+|(vv)+|(ww)+|(yy)+|(zz)+', '');
let counterOfArr=0
const lengthOfstr=str.length;

const permutations = arr => {
  if (arr.length <= 2) return arr.length === 2 ? [arr, [arr[1], arr[0]]] : arr;
  return arr.reduce(
    (acc, item, i) =>
      acc.concat(
        permutations([...arr.slice(0, i), ...arr.slice(i + 1)]).map(val => [
          item,
          ...val,
        ])
      ),
    []
  );
};

  //console.log(arrayOfArrays)
let permutedStr=permutations(splittedStr)
//console.log(permutedStr)
 if(lengthOfstr>1){
   for(let i=0;i<permutedStr.length;i++){
        if(!globalRegex.test(permutedStr[i].join(""))){
                   arrayOfArrays.push(permutedStr[i])      
                    counterOfArr+=1
        }
    }
                    //console.log(counterOfArr)
                    return counterOfArr;
 
 }else{
     return 1
 }
  
     
    
}

permAlone("a")
4

How can I improve my code? Do you know another video or documentation in order to understand recursion for getting the permutation?

5

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