Test results - Codility

Tasks Details

medium

1. MissingInteger

Find the smallest positive integer that does not occur in a given sequence.

100%

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].

Solution

Programming language used JavaScript

Time spent on task 1 minutes

Notes

not defined yet

Code: 10:26:28 UTC, js, verify, result: Passed

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
  const sorted = A.sort((a, b) => a - b)

  let current = 0
  for (let i = 0; i < sorted.length; i++) {
    if (sorted[i] - current > 1) {
      return current + 1
    }
    if (sorted[i] > 0) {
      current = sorted[i]
    }
  }

  return current < 0 ? 1 : current + 1
}

Analysis

▶

example1
first example test

✔

▶

example2
second example test

✔

▶

example3
third example test

✔

Code: 10:26:33 UTC, js, verify, result: Passed

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
  const sorted = A.sort((a, b) => a - b)

  let current = 0
  for (let i = 0; i < sorted.length; i++) {
    if (sorted[i] - current > 1) {
      return current + 1
    }
    if (sorted[i] > 0) {
      current = sorted[i]
    }
  }

  return current < 0 ? 1 : current + 1
}

Analysis

▶

example1
first example test

✔

▶

example2
second example test

✔

▶

example3
third example test

✔

Code: 10:26:35 UTC, js, final, score: 100

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
  const sorted = A.sort((a, b) => a - b)

  let current = 0
  for (let i = 0; i < sorted.length; i++) {
    if (sorted[i] - current > 1) {
      return current + 1
    }
    if (sorted[i] > 0) {
      current = sorted[i]
    }
  }

  return current < 0 ? 1 : current + 1
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N) or O(N * log(N))

▶

example1
first example test

✔

▶

example2
second example test

✔

▶

example3
third example test

✔

▶

extreme_single
a single element

✔

▶

simple
simple test

✔

▶

extreme_min_max_value
minimal and maximal values

✔

▶

positive_only
shuffled sequence of 0...100 and then 102...200

✔

▶

negative_only
shuffled sequence -100 ... -1

✔

▶

medium
chaotic sequences length=10005 (with minus)

✔

▶

large_1
chaotic + sequence 1, 2, ..., 40000 (without minus)

✔

▶

large_2
shuffled sequence 1, 2, ..., 100000 (without minus)

✔

▶

large_3
chaotic + many -1, 1, 2, 3 (with minus)

✔