Smallest Positive Integer Coding Problem (Javascript)

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].

Solution:

function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
A.sort((a, b) => a - b)
let min = 1
for (let i = 0; i < A.length; i++) {
let newValue = A[i]
if (newValue === min) {
min += 1
} else if (newValue > min) {
return min
}
}
return min
}