Test results - Codility

Tasks Details

medium

1. CountDiv

Compute number of integers divisible by k in range [a..b].

Task Score

37%

Correctness

25%

Performance

50%

Write a function:

class Solution { public int solution(int A, int B, int K); }

that, given three integers A, B and K, returns the number of integers within the range [A..B] that are divisible by K, i.e.:

{ i : A ≤ i ≤ B, i mod K = 0 }

For example, for A = 6, B = 11 and K = 2, your function should return 3, because there are three numbers divisible by 2 within the range [6..11], namely 6, 8 and 10.

Write an efficient algorithm for the following assumptions:

A and B are integers within the range [0..2,000,000,000];

K is an integer within the range [1..2,000,000,000];

A ≤ B.

Solution

Programming language used Java 8

Time spent on task 15 minutes

Notes

not defined yet

Task timeline

Code: 08:33:48 UTC, java, verify, result: Failed

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

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

// 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, int B, int K) {
        // write your code in Java SE 8
      
    int start;
    
    
    if(B<A || K==0 || K>B )
        return 0;
    else if(K<A)
        start = A%K +1;
    else if (K<=B)
        start = K;
    
    return (B-start+1)/K+ 1;
          
    }
}

Analysis

Compile error

Solution.java:21: error: variable start might not have been initialized
    return (B-start+1)/K+ 1;
              ^
1 error

Code: 08:34:04 UTC, java, verify, result: Failed

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

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

// 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, int B, int K) {
        // write your code in Java SE 8
      
    int start=0;;
    
    
    if(B<A || K==0 || K>B )
        return 0;
    else if(K<A)
        start = A%K +1;
    else if (K<=B)
        start = K;
    
    return (B-start+1)/K+ 1;
          
    }
}

Analysis

expand all Example tests

▶

example
A = 6, B = 11, K = 2

✘

WRONG ANSWER
got 6 expected 3

0.868 s

WRONG ANSWER, got 6 expected 3

Code: 08:36:11 UTC, java, verify, result: Failed

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

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

// 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, int B, int K) {
        // write your code in Java SE 8
      
    int start=0;;
    
    
    if(B<A || K==0 || K>B )
        return 0;
    else if(K<A)
        start =K* ( A%K +1);
    else if (K<=B)
        start = K;
    
    return (B-start+1)/K+ 1;
          
    }
}

Analysis

expand all Example tests

▶

example
A = 6, B = 11, K = 2

✘

WRONG ANSWER
got 6 expected 3

1.252 s

WRONG ANSWER, got 6 expected 3

Code: 08:36:40 UTC, java, verify, result: Failed

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

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

// 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, int B, int K) {
        // write your code in Java SE 8
      
    int start=0;;
    
    
    if(B<A || K==0 || K>B )
        return 0;
    else if(K<A)
        start =K* ( A%K );
    else if (K<=B)
        start = K;
    
    return (B-start+1)/K+ 1;
          
    }
}

Analysis

expand all Example tests

▶

example
A = 6, B = 11, K = 2

✘

WRONG ANSWER
got 7 expected 3

1.500 s

WRONG ANSWER, got 7 expected 3

Code: 08:39:13 UTC, java, verify, result: Failed

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

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

// 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, int B, int K) {
        // write your code in Java SE 8
      
    int start=0;;
    
    
    if(B<A || K==0 || K>B )
        return 0;
    else if(K<A){
        start = K * ( A%K );
        system.out.println("coucou"+start);
        }
    else if (K<=B)
        start = K;
    
    return (B-start+1)/K+ 1;
          
    }
}

Analysis

Compile error

Solution.java:18: error: package system does not exist
        system.out.println("coucou"+start);
              ^
1 error

Code: 08:39:29 UTC, java, verify, result: Failed

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

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

// 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, int B, int K) {
        // write your code in Java SE 8
      
    int start=0;;
    
    
    if(B<A || K==0 || K>B )
        return 0;
    else if(K<A){
        start = K * ( A%K );
        System.out.println("coucou"+start);
        }
    else if (K<=B)
        start = K;
    
    return (B-start+1)/K+ 1;
          
    }
}

Analysis

expand all Example tests

▶

example
A = 6, B = 11, K = 2

✘

WRONG ANSWER
got 7 expected 3

1.568 s

WRONG ANSWER, got 7 expected 3

stdout:

coucou0

Code: 08:40:59 UTC, java, verify, result: Failed

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

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

// 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, int B, int K) {
        // write your code in Java SE 8
      
    int start=0;;
    
    
    if(B<A || K==0 || K>B )
        return 0;
    else if(K<A){
        start = K * ( A/K );
        System.out.println("coucou"+start);
        }
    else if (K<=B)
        start = K;
    
    return (B-start+1)/K+ 1;
          
    }
}

Analysis

expand all Example tests

▶

example
A = 6, B = 11, K = 2

✘

WRONG ANSWER
got 4 expected 3

1.300 s

WRONG ANSWER, got 4 expected 3

stdout:

coucou6

Code: 08:41:30 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

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

// 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, int B, int K) {
        // write your code in Java SE 8
      
    int start=0;;
    
    
    if(B<A || K==0 || K>B )
        return 0;
    else if(K<A){
        start = K * ( A/K +1);
        System.out.println("coucou"+start);
        }
    else if (K<=B)
        start = K;
    
    return (B-start+1)/K+ 1;
          
    }
}

Analysis

expand all Example tests

▶

example
A = 6, B = 11, K = 2

✔

1.332 s

stdout:

WARNING: producing output may seriously slow down your code!
coucou8

Code: 08:42:23 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

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

// 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, int B, int K) {
        // write your code in Java SE 8
      
    int start=0;;
    
    
    if(B<A || K==0 || K>B )
        return 0;
    else if(K<A){
        start = K * ( A/K +1);
        //System.out.println("coucou"+start);
        }
    else if (K<=B)
        start = K;
    
    return (B-start+1)/K+ 1;
          
    }
}

Analysis

expand all Example tests

▶

example
A = 6, B = 11, K = 2

✔

1.244 s

Code: 08:42:31 UTC, java, final, score: 37

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

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

// 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, int B, int K) {
        // write your code in Java SE 8
      
    int start=0;;
    
    
    if(B<A || K==0 || K>B )
        return 0;
    else if(K<A){
        start = K * ( A/K +1);
        //System.out.println("coucou"+start);
        }
    else if (K<=B)
        start = K;
    
    return (B-start+1)/K+ 1;
          
    }
}

Analysis summary

The following issues have been detected: wrong answers.

Analysis

expand all Example tests

▶

example
A = 6, B = 11, K = 2

✔

1.572 s

expand all Correctness tests

▶

simple
A = 11, B = 345, K = 17

✔

1.616 s

▶

minimal
A, B in {0,1}, K = 11

✘

WRONG ANSWER
got 0 expected 1

1.492 s

WRONG ANSWER, got 0 expected 1

▶

extreme_ifempty
A = 10, B = 10, K in {5,7,20}

✘

WRONG ANSWER
got 1 expected 0

1.456 s

WRONG ANSWER, got 1 expected 0

▶

extreme_endpoints
verify handling of range endpoints, multiple runs

✘

WRONG ANSWER
got 2 expected 3

1.388 s

WRONG ANSWER, got 2 expected 3

expand all Performance tests

▶

big_values
A = 100, B=123M+, K=2

✔

1.476 s

▶

big_values2
A = 101, B = 123M+, K = 10K

✔

1.428 s

▶

big_values3
A = 0, B = MAXINT, K in {1,MAXINT}

✘

WRONG ANSWER
got 1 expected 2

1.416 s

WRONG ANSWER, got 1 expected 2

▶

big_values4
A, B, K in {1,MAXINT}

✘

WRONG ANSWER
got 2 expected 1

1.488 s

WRONG ANSWER, got 2 expected 1