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:

int solution(int A[], int N);

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 C

Time spent on task 6 minutes

Notes

not defined yet

Code: 12:31:12 UTC, java, verify, result: Failed

show code in pop-up

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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");

int solution(int A[], int N) {
    // write your code in C99 (gcc 6.2.0)
    int B[N] = {0};
   
    for (int i = 0 ; i<N ;i++ )
    {
        if (A[i]>0 && A[i]-1<N)
        {
            B[A[i]-1] =1; 
        }
    }
    for (int i = 0 ; i<N ;i++ )
    {
        if ( B[i] == 0)
        {
           return i+1; 
        }
    }
    
    return N+1; 
}

Analysis

Compile error

Solution.java:7: error: class, interface, or enum expected
int solution(int A[], int N) {
^
Solution.java:11: error: class, interface, or enum expected
    for (int i = 0 ; i<N ;i++ )
    ^
Solution.java:11: error: class, interface, or enum expected
    for (int i = 0 ; i<N ;i++ )
                     ^
Solution.java:11: error: class, interface, or enum expected
    for (int i = 0 ; i<N ;i++ )
                          ^
Solution.java:16: error: class, interface, or enum expected
        }
        ^
Solution.java:18: error: class, interface, or enum expected
    for (int i = 0 ; i<N ;i++ )
                     ^
Solution.java:18: error: class, interface, or enum expected
    for (int i = 0 ; i<N ;i++ )
                          ^
Solution.java:23: error: class, interface, or enum expected
        }
        ^
Solution.java:27: error: class, interface, or enum expected
}
^
9 errors

Code: 12:31:34 UTC, c, verify, result: Failed

show code in pop-up

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// you can write to stdout for debugging purposes, e.g.
// printf("this is a debug message\n");

int solution(int A[], int N) {
    // write your code in C99 (gcc 6.2.0)
    int B[N] = {0};
   
    for (int i = 0 ; i<N ;i++ )
    {
        if (A[i]>0 && A[i]-1<N)
        {
            B[A[i]-1] =1; 
        }
    }
    for (int i = 0 ; i<N ;i++ )
    {
        if ( B[i] == 0)
        {
           return i+1; 
        }
    }
    
    return N+1; 
}

Analysis

Compile error

func.c: In function 'solution':
func.c:6:5: error: variable-sized object may not be initialized
     int B[N] = {0};
     ^~~
func.c:6:17: warning: excess elements in array initializer
     int B[N] = {0};
                 ^
func.c:6:17: note: (near initialization for 'B')

Code: 12:32:39 UTC, c, verify, result: Failed

show code in pop-up

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// you can write to stdout for debugging purposes, e.g.
// printf("this is a debug message\n");

int solution(int A[], int N) {
    // write your code in C99 (gcc 6.2.0)
    int B[N]; 
    B= {0};
    for (int i = 0 ; i<N ;i++ )
    {
        if (A[i]>0 && A[i]-1<N)
        {
            B[A[i]-1] =1; 
        }
    }
    for (int i = 0 ; i<N ;i++ )
    {
        if ( B[i] == 0)
        {
           return i+1; 
        }
    }
    
    return N+1; 
}

Analysis

Compile error

func.c: In function 'solution':
func.c:7:8: error: expected expression before '{' token
     B= {0};
        ^

Code: 12:33:10 UTC, c, verify, result: Failed

show code in pop-up

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// you can write to stdout for debugging purposes, e.g.
// printf("this is a debug message\n");

int solution(int A[], int N) {
    // write your code in C99 (gcc 6.2.0)
    int B[N] = {0};

    for (int i = 0 ; i<N ;i++ )
    {
        if (A[i]>0 && A[i]-1<N)
        {
            B[A[i]-1] =1; 
        }
    }
    for (int i = 0 ; i<N ;i++ )
    {
        if ( B[i] == 0)
        {
           return i+1; 
        }
    }
    
    return N+1; 
}

Analysis

Compile error

func.c: In function 'solution':
func.c:6:5: error: variable-sized object may not be initialized
     int B[N] = {0};
     ^~~
func.c:6:17: warning: excess elements in array initializer
     int B[N] = {0};
                 ^
func.c:6:17: note: (near initialization for 'B')

Code: 12:34:09 UTC, c, verify, result: Failed

show code in pop-up

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// you can write to stdout for debugging purposes, e.g.
// printf("this is a debug message\n");

int solution(int A[], int N) {
    // write your code in C99 (gcc 6.2.0)
    int B[N] = {0};
    
    memset( B, 0, N*sizeof(int) );
    for (int i = 0 ; i<N ;i++ )
    {
        if (A[i]>0 && A[i]-1<N)
        {
            B[A[i]-1] =1; 
        }
    }
    for (int i = 0 ; i<N ;i++ )
    {
        if ( B[i] == 0)
        {
           return i+1; 
        }
    }
    
    return N+1; 
}

Analysis

Compile error

func.c: In function 'solution':
func.c:6:5: error: variable-sized object may not be initialized
     int B[N] = {0};
     ^~~
func.c:6:17: warning: excess elements in array initializer
     int B[N] = {0};
                 ^
func.c:6:17: note: (near initialization for 'B')
func.c:8:5: warning: implicit declaration of function 'memset' [-Wimplicit-function-declaration]
     memset( B, 0, N*sizeof(int) );
     ^~~~~~
func.c:8:5: warning: incompatible implicit declaration of built-in function 'memset'
func.c:8:5: note: include '<string.h>' or provide a declaration of 'memset'

Code: 12:34:22 UTC, c, verify, result: Passed

show code in pop-up

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// you can write to stdout for debugging purposes, e.g.
// printf("this is a debug message\n");

int solution(int A[], int N) {
    // write your code in C99 (gcc 6.2.0)
    int B[N];
    
    memset( B, 0, N*sizeof(int) );
    for (int i = 0 ; i<N ;i++ )
    {
        if (A[i]>0 && A[i]-1<N)
        {
            B[A[i]-1] =1; 
        }
    }
    for (int i = 0 ; i<N ;i++ )
    {
        if ( B[i] == 0)
        {
           return i+1; 
        }
    }
    
    return N+1; 
}

Analysis

expand all Example tests

▶

example
example (without minus)

✔

0.008 s

Code: 12:35:15 UTC, c, verify, result: Passed

show code in pop-up

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// you can write to stdout for debugging purposes, e.g.
// printf("this is a debug message\n");
#include <string.h>

int solution(int A[], int N) {
    // write your code in C99 (gcc 6.2.0)
    int B[N];
    
    memset( B, 0, N*sizeof(int) );
    for (int i = 0 ; i<N ;i++ )
    {
        if (A[i]>0 && A[i]-1<N)
        {
            B[A[i]-1] =1; 
        }
    }
    for (int i = 0 ; i<N ;i++ )
    {
        if ( B[i] == 0)
        {
           return i+1; 
        }
    }
    
    return N+1; 
}

Analysis

expand all Example tests

▶

example
example (without minus)

✔

0.004 s

Code: 12:36:31 UTC, c, verify, result: Passed

show code in pop-up

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// you can write to stdout for debugging purposes, e.g.
// printf("this is a debug message\n");
#include <string.h>

int solution(int A[], int N) {
    // write your code in C99 (gcc 6.2.0)
    int B[N];
    
    memset( B, 0, N*sizeof(int) );
    for (int i = 0 ; i<N ;i++ )
    {
        if (A[i]>0 && A[i]-1<N)
        {
            B[A[i]-1] =1; 
        }
    }
    for (int i = 0 ; i<N ;i++ )
    {
        if ( B[i] == 0)
        {
           return i+1; 
        }
    }
    
    return N+1; 
}

Analysis

expand all Example tests

▶

example
example (without minus)

✔

0.009 s

Code: 12:36:35 UTC, c, final, score: 100

show code in pop-up

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// you can write to stdout for debugging purposes, e.g.
// printf("this is a debug message\n");
#include <string.h>

int solution(int A[], int N) {
    // write your code in C99 (gcc 6.2.0)
    int B[N];
    
    memset( B, 0, N*sizeof(int) );
    for (int i = 0 ; i<N ;i++ )
    {
        if (A[i]>0 && A[i]-1<N)
        {
            B[A[i]-1] =1; 
        }
    }
    for (int i = 0 ; i<N ;i++ )
    {
        if ( B[i] == 0)
        {
           return i+1; 
        }
    }
    
    return N+1; 
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N)

expand all Example tests

▶

example
example (without minus)

✔

0.008 s

expand all Correctness tests

▶

extreme_single
a single element

✔

0.008 s

0.009 s

0.008 s

▶

simple
simple test

✔

0.008 s

▶

extreme_min_max_int
MININT and MAXINT (with minus)

✔

0.009 s

0.008 s

▶

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

✔

0.009 s

▶

negative_only
shuffled sequence -100 ... -1

✔

0.008 s

expand all Performance tests

▶

medium
chaotic sequences length=10005 (with minus)

✔

0.009 s

0.010 s

▶

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

✔

0.019 s

▶

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

✔

0.022 s

▶

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

✔

0.016 s