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 13 minutes

Notes

not defined yet

Task timeline

Code: 12:04:00 UTC, java, verify, result: Passed

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");
import java.util.Arrays;
class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        Arrays.sort(A);
        int j=1;
        for(int i=0; i<A.length; i++) {
            if(A[i] <= 0)
                continue;
            if(A[i] == j)
                j++;
            else if(A[i] > j)
                break;
        }
        return j;
    }
}

Analysis

▶

example
example (without minus)

✔

Code: 12:04:13 UTC, java, verify, result: Passed

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");
import java.util.Arrays;
class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        Arrays.sort(A);
        int j=1;
        for(int i=0; i<A.length; i++) {
            if(A[i] <= 0)
                continue;
            if(A[i] == j)
                j++;
            else if(A[i] > j)
                break;
        }
        return j;
    }
}

Analysis

▶

example
example (without minus)

✔

Code: 12:04:26 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");
import java.util.Arrays;
class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        Arrays.sort(A);
        int j=1;
        for(int i=0; i<A.length; i++) {
            if(A[i] <= 0)
                continue;
            if(A[i] == j)
                j++;
            else if(A[i] > j)
                break;
        }
        return j;
    }
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N)

▶

example
example (without minus)

✔

▶

extreme_single
a single element

✔

▶

simple
simple test

✔

▶

extreme_min_max_int
MININT and MAXINT (with minus)

✔

▶

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)

✔