Changes to make for the function which takes as argument a sequence and returns a list of items without any elements with the same value

Question

Implement the function unique_in_order which takes as argument a sequence and returns a list of items without any elements with the same value next to each other and preserving the original order of elements. For example:

uniqueInOrder('AAAABBBCCDAABBB') == ['A', 'B', 'C', 'D', 'A', 'B']

var uniqueInOrder = function(it) {
  let n = 0;
  let arr = [];
  let i = 0;
  let m = 0;
  length = it.length;
  if (length == 0) {
    return arr
  } else {
    if (n == 0) {
      arr.push(it[0]);
      n += 1;
    }
    while (n < length) {

      if (arr[i] != it[m + 1]) {
        arr.push(it[m + 1])
        i += 1;
        n += 1
      } else {
        m += 1
        n += 1
      }

    }
    return arr
  }
}
console.log(uniqueInOrder('AAAABBBCCDAABBB'));

should reduce duplicates:

Expected: '[\'A\', \'B\', \'C\', \'D\', \'A\', \'B\']'

instead got: '[\'A\', \'B\', \'C\', \'D\', \'A\']'

should treat lowercase as different from uppercase:

Expected: '[\'A\', \'B\', \'C\', \'c\', \'A\', \'D\']'

instead got: '[\'A\', \'B\', \'C\', \'c\']'

Answer 1

You need to increase m at each iteration not just when a match is not found. The same goes for n

var uniqueInOrder = function(it) {
  let n = 0;
  let arr = [];
  let i = 0;
  let m = 0;
  length = it.length;
  if (length == 0) {
    return arr
  } else {
    if (n == 0) {
      arr.push(it[0]);
      n += 1;
    }
    while (n < length) {
      if (arr[i] != it[m + 1]) {
        arr.push(it[m + 1])
        i += 1;
        n += 1
      }
      m += 1
      n += 1
    }
    return arr
  }
}
console.log(uniqueInOrder('AAAABBBCCDAABBB'));

Answer 2

The Solution can be implemented using

• Using rest & spread operator
• Checking if the input is a string or an array

Below is the working code

  var uniqueInOrder=function(iterable){
  if (typeof iterable === 'string') {
            let newArray = [];
            const [...arr] = [...iterable];
            for (let i = 0; i < arr.length; i++) {
                if (arr[i] != arr[i + 1]) {
                    newArray.push(arr[i])
                }
            }
             return newArray;
          }
  else{
    let newArray = [];
    for (let i = 0; i < iterable.length; i++) {
                if (iterable[i] != iterable[i + 1]) {
                    newArray.push(arr[i])
                }
            }
             return newArray;
  }
}