Steamroller problem

JavaScript
#1

Tell us what’s happening:
what is wrong with this code?..test cases are not passing…although m getting output same as the expected output

Your code so far

var new_arr=[];
function steamrollArray(arr) {
  for(var i=0;i<arr.length;i++){
    if(!Array.isArray(arr[i]))
      new_arr.push(arr[i]);
    else steamrollArray(arr[i]);
  }
  return new_arr;
}

steamrollArray([1, {}, [3, [[4]]]]);

Your browser information:

Your Browser User Agent is: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.139 Safari/537.36.

Link to the challenge:
https://www.freecodecamp.org/challenges/steamroller

#2

Hi @ABHI5995

Your logic is fine, the problem is you’re declaring the new_arr variable in the global scope, so when the tests run in sequence, they all add to the same array in memory which ultimately pollutes the answer.

You can test this by commenting out your call to steamrollArray and re-running the tests, the first one should pass then the last 3 should fail.

1 Like
#3

yuppp now i understood the issue…can u help me in getting out of it?

#4

You could create a function inside the steamrollArray function that wraps the for loop. Then declare the new_arr variable inside steamrollArray and call the nested function before the return statement, passing in the array to it.

Kinda like this if your stuck on the implementation:

function steamrollArray(arr) {
  var new_arr=[];
  
  function steamRoll(arr) {
    for(var i=0;i<arr.length;i++){
      if(!Array.isArray(arr[i]))
        new_arr.push(arr[i]);
      else steamRoll(arr[i]);
    }
  }
  
  steamRoll(arr);
  
  return new_arr;
}

Alternatively, rather than mutating an array, you could look at doing something functional, like using reduce. You should be able to adapt your existing code fairly easily to use reduce.

#5

thank u so much sir!

1 Like
#6