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:

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].

Solution

Programming language used Java 8

Time spent on task 1 minutes

Notes

not defined yet

Task timeline

Code: 09:09:45 UTC, java, verify, result: Passed

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// you can also use imports, for example:
// import java.util.*;

// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");

class Solution {
    public int solution(int[] A) {
        boolean[] B = new boolean[1000001];
        java.util.Arrays.fill(B, false);
        for (int i = 0; i < A.length; i++) {
            if (A[i] > 0) {
                B[A[i]] = true;
            }
        }
        for (int j = 1; j < B.length; j++) {
            if (!B[j]) return j;
        }

        return 1000001;
    }
}

Analysis

▶

example1
first example test

✔

▶

example2
second example test

✔

▶

example3
third example test

✔

Code: 09:09:50 UTC, java, final, score: 100

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

// you can also use imports, for example:
// import java.util.*;

// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");

class Solution {
    public int solution(int[] A) {
        boolean[] B = new boolean[1000001];
        java.util.Arrays.fill(B, false);
        for (int i = 0; i < A.length; i++) {
            if (A[i] > 0) {
                B[A[i]] = true;
            }
        }
        for (int j = 1; j < B.length; j++) {
            if (!B[j]) return j;
        }

        return 1000001;
    }
}

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)

✔