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MissingInteger (Lesson 4)

Instructions​

This is a demo task.

Write a function:

function solution(A);

that, given an array A of N integers, returns the smallest positive integer (greater than 0) that does not occur in A.

For example, given A = [1, 3, 6, 4, 1, 2], the function should return 5.

Given A = [1, 2, 3], the function should return 4.

Given A = [−1, −3], the function should return 1.

Write an efficient algorithm for the following assumptions:

  • N is an integer within the range [1..100,000];
  • each element of array A is an integer within the range [−1,000,000..1,000,000]. range [1..N + 1].

Solution​

function solution(A) {
  let answer = 1;
  const removeOverlapSet = new Set(A);

  for (const value of removeOverlapSet) {
    if (!removeOverlapSet.has(answer)) break;
    answer += 1;
  }
  return answer;
}
  1. 중복 제거 된 removeOverlapSet을 순회하면서 1부터 있는지 없는지 체크한다.
  2. 없는 순간 그 값을 뱉어낸다.

Review​

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References​