codility-test-sample.js

/*
Write a function:

class Solution { public int solution(int[] 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].
*/

function solution(A) {
  // write your code in JavaScript (Node.js 8.9.4)
  const max = A.reduce(function(a, b) {
    return Math.max(a, b);
  });

  if (max <= 0) {
    return 1;
  }

  for (i = 1; i <= max; i++) {
    if (!A.includes(i)) {
      return i;
    }
  }

  return max + 1;
}

var A = [1, 3, 6, 4, 1, 2];
console.log(solution(A) === 5);

var A = [1, 2, 3];
console.log(solution(A) === 4);

var A = [-1, -3];
console.log(solution(A) === 1);

14 answer