Test results - Codility

Tasks Details

medium

1. MissingInteger

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

Task Score

100%

Correctness

100%

Performance

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 4 minutes

Notes

not defined yet

Code: 07:04:05 UTC, java, verify, result: Passed

show code in pop-up

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

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

class Solution {
     public int solution(int[] A) {     
     HashSet<Integer> temp = new HashSet<>(); // to add just positives
     int max = 1;
     for (int i =0; i < A.length; ++i) {
         int current = A[i];
         if (current < 0 ) {
             continue;
         } else {
             temp.add(current);
             if( max <= current) {
                 max = current;
             }
         }
     }
     max = Math.max(max, A.length); // taking into account arrays with random elements
     for(int i = 1; i <= max ; ++i) {
         boolean contains = temp.contains(i);
         if(!contains) {
             return i;
         }
     }
     return A.length + 1; // array is complete
 }
}

Analysis

expand all Example tests

▶

example
example (without minus)

✔

1.329 s

Code: 07:05:22 UTC, java, verify, result: Passed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

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

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

class Solution {
     public int solution(int[] A) {     
     HashSet<Integer> positives = new HashSet<>(); // to add just positives
     int max = 1, length = A.length;
     for (int i =0; i < length; ++i) {
         int current = A[i];
         if (current < 0 ) {
             continue;
         } else {
             positives.add(current);
             if( max <= current) {
                 max = current;
             }
         }
     }
     max = Math.max(max, length); // taking into account arrays with random elements
     for(int i = 1; i <= max ; ++i) {         
         if(!positives.contains(i)) {
             return i;
         }
     }
     return length + 1; // array is complete
 }
}

Analysis

expand all Example tests

▶

example
example (without minus)

✔

1.337 s

Code: 07:06:58 UTC, java, verify, result: Passed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

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

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

class Solution {
    // (-2,1) = 2
    // (2) = 1
    // (1) = 2
    // (1,2,4) = 3
    // (1,2,3) = 4
    public int solution(int[] A) {     
        HashSet<Integer> positives = new HashSet<>(); // to add just positives
        int max = 1, length = A.length;
        for (int i =0; i < length; ++i) {
             int current = A[i];
            if (current < 0 ) {
                continue;
            } else {
                 positives.add(current);
                if( max <= current) {
                    max = current;
                }
            }
        }
        max = Math.max(max, length); // taking into account arrays with random elements
        for(int i = 1; i <= max ; ++i) {         
             if(!positives.contains(i)) {
                 return i;
            }
        }
        return length + 1; // array is complete
    }
}

Analysis

expand all Example tests

▶

example
example (without minus)

✔

1.324 s

Code: 07:07:09 UTC, java, verify, result: Passed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

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

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

class Solution {
    // (-2,1) = 2
    // (2) = 1
    // (1) = 2
    // (1,2,4) = 3
    // (1,2,3) = 4
    public int solution(int[] A) {     
        HashSet<Integer> positives = new HashSet<>(); // to add just positives
        int max = 1, length = A.length;
        for (int i =0; i < length; ++i) {
             int current = A[i];
            if (current < 0 ) {
                continue;
            } else {
                 positives.add(current);
                if( max <= current) {
                    max = current;
                }
            }
        }
        max = Math.max(max, length); // taking into account arrays with random elements
        for(int i = 1; i <= max ; ++i) {         
             if(!positives.contains(i)) {
                 return i;
            }
        }
        return length + 1; // array is complete
    }
}

Analysis

expand all Example tests

▶

example
example (without minus)

✔

1.321 s

Code: 07:07:14 UTC, java, final, score: 100

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

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

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

class Solution {
    // (-2,1) = 2
    // (2) = 1
    // (1) = 2
    // (1,2,4) = 3
    // (1,2,3) = 4
    public int solution(int[] A) {     
        HashSet<Integer> positives = new HashSet<>(); // to add just positives
        int max = 1, length = A.length;
        for (int i =0; i < length; ++i) {
             int current = A[i];
            if (current < 0 ) {
                continue;
            } else {
                 positives.add(current);
                if( max <= current) {
                    max = current;
                }
            }
        }
        max = Math.max(max, length); // taking into account arrays with random elements
        for(int i = 1; i <= max ; ++i) {         
             if(!positives.contains(i)) {
                 return i;
            }
        }
        return length + 1; // array is complete
    }
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N)

expand all Example tests

▶

example
example (without minus)

✔

1.343 s

expand all Correctness tests

▶

extreme_single
a single element

✔

1.338 s

1.335 s

1.347 s

▶

simple
simple test

✔

1.338 s

1.343 s

▶

extreme_min_max_int
MININT and MAXINT (with minus)

✔

1.327 s

1.338 s

▶

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

✔

1.343 s

▶

negative_only
shuffled sequence -100 ... -1

✔

1.353 s

expand all Performance tests

▶

medium
chaotic sequences length=10005 (with minus)

✔

1.377 s

1.352 s

1.404 s

▶

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

✔

1.760 s

▶

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

✔

1.830 s

1.800 s

▶

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

✔

1.603 s