Missing integer variation - O(n) solution needed [closed]

Answer 1

JavaScript 100%

function solution(A) {
  let sortedOb = {};
  let biggest = 0;

  A.forEach(el => {
    if (el > 0) {
      sortedOb[el] = 0;
      biggest = el > biggest ? el : biggest;
    }
  });
  let arr = Object.keys(sortedOb).map(el => +el);
  if (arr.length == 0) return 1;

  for(let i = 1; i <= biggest; i++) {
    if (sortedOb[i] === undefined) return i;
  }
  return biggest + 1;
}