Test results - Codility

Tasks Details

easy

1. Dominator

Find an index of an array such that its value occurs at more than half of indices in the array.

Task Score

75%

Correctness

87%

Performance

50%

An array A consisting of N integers is given. The dominator of array A is the value that occurs in more than half of the elements of A.

For example, consider array A such that

A[0] = 3 A[1] = 4 A[2] = 3 A[3] = 2 A[4] = 3 A[5] = -1 A[6] = 3 A[7] = 3

The dominator of A is 3 because it occurs in 5 out of 8 elements of A (namely in those with indices 0, 2, 4, 6 and 7) and 5 is more than a half of 8.

Write a function

class Solution { public int solution(int[] A); }

that, given an array A consisting of N integers, returns index of any element of array A in which the dominator of A occurs. The function should return −1 if array A does not have a dominator.

For example, given array A such that

A[0] = 3 A[1] = 4 A[2] = 3 A[3] = 2 A[4] = 3 A[5] = -1 A[6] = 3 A[7] = 3

the function may return 0, 2, 4, 6 or 7, as explained above.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [0..100,000];

each element of array A is an integer within the range [−2,147,483,648..2,147,483,647].

Solution

Programming language used Java 8

Time spent on task 16 minutes

Notes

not defined yet

Task timeline

Code: 14:40:36 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) {
        // write your code in Java SE 8
        int len=A.length;
        for(int i=0;i<len;i++){
            System.out.println(A[i]);
        }
        return 0;
    }
}

Analysis

expand all Example tests

▶

example
example test

✔

1.309 s

stdout:

Code: 14:49:50 UTC, java, verify, result: Failed

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

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        int len=A.length;
        int ind=-1;
        for(int i=0;i<(len/2)+;i++){
            for(int j=len/2;j<len;j++){
                if(A[i]==A[j]){
                    count++;
                }
            if(count>(len/2)){
                ind=i;
            }
            }
        }
        return i;
    }
}

Analysis

Compile error

Solution.java:12: error: illegal start of expression
        for(int i=0;i<(len/2)+;i++){
                              ^
1 error

Code: 14:50:07 UTC, java, verify, result: Failed

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

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        int len=A.length;
        int ind=-1;
        for(int i=0;i<(len/2)+1;i++){
            for(int j=len/2;j<len;j++){
                if(A[i]==A[j]){
                    count++;
                }
            if(count>(len/2)){
                ind=i;
            }
            }
        }
        return i;
    }
}

Analysis

Compile error

Solution.java:15: error: cannot find symbol
                    count++;
                    ^
  symbol:   variable count
  location: class Solution
Solution.java:17: error: cannot find symbol
            if(count>(len/2)){
               ^
  symbol:   variable count
  location: class Solution
Solution.java:22: error: cannot find symbol
        return i;
               ^
  symbol:   variable i
  location: class Solution
3 errors

Code: 14:51:13 UTC, java, verify, result: Failed

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

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        int len=A.length;
        int ind=-1;
        for(int i=0;i<(len/2)+1;i++){
            for(int j=len/2;j<len;j++){
                if(A[i]==A[j]){
                    count++;
                }
            }
            if(count>(len/2)){
                ind=i;
            }
        }
        return i;
    }
}

Analysis

Compile error

Solution.java:15: error: cannot find symbol
                    count++;
                    ^
  symbol:   variable count
  location: class Solution
Solution.java:18: error: cannot find symbol
            if(count>(len/2)){
               ^
  symbol:   variable count
  location: class Solution
Solution.java:22: error: cannot find symbol
        return i;
               ^
  symbol:   variable i
  location: class Solution
3 errors

Code: 14:51:26 UTC, java, verify, result: Failed

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

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        int len=A.length;
        int ind=-1;
        for(int i=0;i<(len/2)+1;i++){
            for(int j=len/2;j<len;j++){
                if(A[i]==A[j]){
                    count++;
                }
            }
            if(count>(len/2)){
                ind=i;
            }
        }
        return ind;
    }
}

Analysis

Compile error

Solution.java:15: error: cannot find symbol
                    count++;
                    ^
  symbol:   variable count
  location: class Solution
Solution.java:18: error: cannot find symbol
            if(count>(len/2)){
               ^
  symbol:   variable count
  location: class Solution
2 errors

Code: 14:51:43 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

// 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) {
        // write your code in Java SE 8
        int len=A.length;
        int ind=-1;
        int count=0;
        for(int i=0;i<(len/2)+1;i++){
            for(int j=len/2;j<len;j++){
                if(A[i]==A[j]){
                    count++;
                }
            }
            if(count>(len/2)){
                ind=i;
            }
        }
        return ind;
    }
}

Analysis

expand all Example tests

▶

example
example test

✔

0.989 s

Code: 14:52:22 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

// 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) {
        // write your code in Java SE 8
        int len=A.length;
        int ind=-1;
        int count=0;
        for(int i=0;i<(len/2)+1;i++){
            for(int j=len/2;j<len;j++){
                if(A[i]==A[j]){
                    count++;
                }
            }
            if(count>(len/2)){
                ind=i;
            }
        }
        return ind;
    }
}

User test case 1:

[1, 2, 4, 5, 6, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2]

Analysis

expand all Example tests

▶

example
example test

✔

1.331 s

expand all User tests

▶

test_data1

✔

1.332 s

OK
function result: 8

Code: 14:53:13 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

// 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) {
        // write your code in Java SE 8
        int len=A.length;
        int ind=-1;
        int count=0;
        for(int i=0;i<(len/2)+1;i++){
            for(int j=len/2;j<len;j++){
                if(A[i]==A[j]){
                    count++;
                }
            }
            if(count>(len/2)){
                ind=i;
            }
        }
        return ind;
    }
}

User test case 1:

[1, 2, 4, 5, 6, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2]

User test case 2:

[3, 1, 3, 2, 3, -1, 3, 3]

Analysis

expand all Example tests

▶

example
example test

✔

1.216 s

expand all User tests

▶

test_data1

✔

1.151 s

OK
function result: 8

▶

test_data2

✔

1.357 s

OK
function result: 4

Code: 14:53:35 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

// 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) {
        // write your code in Java SE 8
        int len=A.length;
        int ind=-1;
        int count=0;
        for(int i=0;i<(len/2)+1;i++){
            for(int j=len/2;j<len;j++){
                if(A[i]==A[j]){
                    count++;
                }
            }
            if(count>(len/2)){
                ind=i;
            }
        }
        return ind;
    }
}

User test case 1:

[1, 2, 4, 5, 6, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2]

User test case 2:

[3, 1, 3, 2, 3, -1, 3, 3]

Analysis

expand all Example tests

▶

example
example test

✔

1.122 s

expand all User tests

▶

test_data1

✔

1.041 s

OK
function result: 8

▶

test_data2

✔

0.991 s

OK
function result: 4

Code: 14:53:43 UTC, java, final, score: 75

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

// 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) {
        // write your code in Java SE 8
        int len=A.length;
        int ind=-1;
        int count=0;
        for(int i=0;i<(len/2)+1;i++){
            for(int j=len/2;j<len;j++){
                if(A[i]==A[j]){
                    count++;
                }
            }
            if(count>(len/2)){
                ind=i;
            }
        }
        return ind;
    }
}

Analysis summary

The following issues have been detected: wrong answers, timeout errors.

For example, for the input [1, 2, 1] the solution returned a wrong answer (got 1, but element is not a dominator, value 2 has only 1 occurences (n=3)).

Analysis

expand all Example tests

▶

example
example test

✔

1.353 s

expand all Correctness tests

▶

small_nondominator
all different and all the same elements

✔

1.362 s

1.210 s

▶

small_half_positions
half elements the same, and half + 1 elements the same

✔

1.034 s

1.028 s

▶

small
small test

✘

WRONG ANSWER
got 1, but element is not a dominator, value 2 has only 1 occurences (n=3)

0.972 s

WRONG ANSWER, got 1, but element is not a dominator, value 2 has only 1 occurences (n=3)

0.995 s

▶

small_pyramid
decreasing and plateau, small

✔

1.342 s

▶

extreme_empty_and_single_item
empty and single element arrays

✔

1.349 s

1.356 s

▶

extreme_half1
array with exactly N/2 values 1, N even + [0,0,1,1,1]

✔

1.347 s

1.348 s

▶

extreme_half2
array with exactly floor(N/2) values 1, N odd + [0,0,1,1,1]

✔

1.353 s

1.354 s

▶

extreme_half3
array with exactly ceil(N/2) values 1 + [0,0,1,1,1]

✔

1.346 s

1.356 s

expand all Performance tests

▶

medium_pyramid
decreasing and plateau, medium

✔

1.789 s

▶

large_pyramid
decreasing and plateau, large

✘

TIMEOUT ERROR
running time: >9.00 sec., time limit: 3.37 sec.

9.000 s

TIMEOUT ERROR, running time: >9.00 sec., time limit: 3.37 sec.

▶

medium_random
random test with dominator, N = 10,000

✔

1.852 s

▶

large_random
random test with dominator, N = 100,000

✘

TIMEOUT ERROR
running time: >9.00 sec., time limit: 3.59 sec.

9.000 s

TIMEOUT ERROR, running time: >9.00 sec., time limit: 3.59 sec.