Test results - Codility

Tasks Details

easy

1. TapeEquilibrium

Minimize the value |(A[0] + ... + A[P-1]) - (A[P] + ... + A[N-1])|.

Task Score

100%

Correctness

100%

Performance

100%

A non-empty array A consisting of N integers is given. Array A represents numbers on a tape.

Any integer P, such that 0 < P < N, splits this tape into two non-empty parts: A[0], A[1], ..., A[P − 1] and A[P], A[P + 1], ..., A[N − 1].

The difference between the two parts is the value of: |(A[0] + A[1] + ... + A[P − 1]) − (A[P] + A[P + 1] + ... + A[N − 1])|

In other words, it is the absolute difference between the sum of the first part and the sum of the second part.

For example, consider array A such that:

A[0] = 3 A[1] = 1 A[2] = 2 A[3] = 4 A[4] = 3

We can split this tape in four places:

P = 1, difference = |3 − 10| = 7

P = 2, difference = |4 − 9| = 5

P = 3, difference = |6 − 7| = 1

P = 4, difference = |10 − 3| = 7

Write a function:

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

that, given a non-empty array A of N integers, returns the minimal difference that can be achieved.

For example, given:

A[0] = 3 A[1] = 1 A[2] = 2 A[3] = 4 A[4] = 3

the function should return 1, as explained above.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [2..100,000];

each element of array A is an integer within the range [−1,000..1,000].

Solution

Programming language used Java 8

Time spent on task 3 minutes

Notes

not defined yet

Task timeline

Code: 11:06:30 UTC, java, autosave

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.*;

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        int min = 1000;
        int preSum = A[0];
        int postSum = 0;

        for(int i=1; i<A.length; i++){
            postSum += A[i];
        }

        for(int i=1; i<A.length; i++){
            if( Math.abs(preSum - postSum) < min ){
                min = Math.abs(preSum - postSum);
            }
            preSum += A[i];
            postSum -= A[i];
        }

        return min;
    }
}

Code: 11:06:42 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.*;

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        int min = 1000;
        int preSum = A[0];
        int postSum = 0;

        for(int i=1; i<A.length; i++){
            postSum += A[i];
        }

        for(int i=1; i<A.length; i++){
            if( Math.abs(preSum - postSum) < min ){
                min = Math.abs(preSum - postSum);
            }
            preSum += A[i];
            postSum -= A[i];
        }

        return min;
    }
}

User test case 1:

[1000, -1000]

Analysis

expand all Example tests

▶

example
example test

✔

0.008 s

expand all User tests

▶

test_data1

✔

0.008 s

OK
function result: 1000

Code: 11:06:56 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.*;

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        int min = 1001;
        int preSum = A[0];
        int postSum = 0;

        for(int i=1; i<A.length; i++){
            postSum += A[i];
        }

        for(int i=1; i<A.length; i++){
            if( Math.abs(preSum - postSum) < min ){
                min = Math.abs(preSum - postSum);
            }
            preSum += A[i];
            postSum -= A[i];
        }

        return min;
    }
}

User test case 1:

[1000, -1000]

Analysis

expand all Example tests

▶

example
example test

✔

0.008 s

expand all User tests

▶

test_data1

✔

0.008 s

OK
function result: 1001

Code: 11:07:09 UTC, java, autosave

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.*;

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        int min = 10;
        int preSum = A[0];
        int postSum = 0;

        for(int i=1; i<A.length; i++){
            postSum += A[i];
        }

        for(int i=1; i<A.length; i++){
            if( Math.abs(preSum - postSum) < min ){
                min = Math.abs(preSum - postSum);
            }
            preSum += A[i];
            postSum -= A[i];
        }

        return min;
    }
}

Code: 11:07:11 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.*;

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        int min = 99999;
        int preSum = A[0];
        int postSum = 0;

        for(int i=1; i<A.length; i++){
            postSum += A[i];
        }

        for(int i=1; i<A.length; i++){
            if( Math.abs(preSum - postSum) < min ){
                min = Math.abs(preSum - postSum);
            }
            preSum += A[i];
            postSum -= A[i];
        }

        return min;
    }
}

User test case 1:

[1000, -1000]

Analysis

expand all Example tests

▶

example
example test

✔

0.008 s

expand all User tests

▶

test_data1

✔

0.008 s

OK
function result: 2000

Code: 11:08:01 UTC, java, autosave

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.*;

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        int min = I;
        int preSum = A[0];
        int postSum = 0;

        for(int i=1; i<A.length; i++){
            postSum += A[i];
        }

        for(int i=1; i<A.length; i++){
            if( Math.abs(preSum - postSum) < min ){
                min = Math.abs(preSum - postSum);
            }
            preSum += A[i];
            postSum -= A[i];
        }

        return min;
    }
}

Code: 11:08:11 UTC, java, autosave

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.*;

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        int min = Integer.MAX_;
        int preSum = A[0];
        int postSum = 0;

        for(int i=1; i<A.length; i++){
            postSum += A[i];
        }

        for(int i=1; i<A.length; i++){
            if( Math.abs(preSum - postSum) < min ){
                min = Math.abs(preSum - postSum);
            }
            preSum += A[i];
            postSum -= A[i];
        }

        return min;
    }
}

Code: 11:08:29 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.*;

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        int min = Integer.MAX_VALUE;
        int preSum = A[0];
        int postSum = 0;

        for(int i=1; i<A.length; i++){
            postSum += A[i];
        }

        for(int i=1; i<A.length; i++){
            if( Math.abs(preSum - postSum) < min ){
                min = Math.abs(preSum - postSum);
            }
            preSum += A[i];
            postSum -= A[i];
        }

        return min;
    }
}

User test case 1:

[1000, -1000]

Analysis

expand all Example tests

▶

example
example test

✔

0.008 s

expand all User tests

▶

test_data1

✔

0.012 s

OK
function result: 2000

Code: 11:08:45 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.*;

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        int min = Integer.MAX_VALUE;
        int preSum = A[0];
        int postSum = 0;

        for(int i=1; i<A.length; i++){
            postSum += A[i];
        }

        for(int i=1; i<A.length; i++){
            if( Math.abs(preSum - postSum) < min ){
                min = Math.abs(preSum - postSum);
            }
            preSum += A[i];
            postSum -= A[i];
        }

        return min;
    }
}

User test case 1:

[1000, -1000]

Analysis

expand all Example tests

▶

example
example test

✔

0.004 s

expand all User tests

▶

test_data1

✔

0.008 s

OK
function result: 2000

Code: 11:08:50 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

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

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        int min = Integer.MAX_VALUE;
        int preSum = A[0];
        int postSum = 0;

        for(int i=1; i<A.length; i++){
            postSum += A[i];
        }

        for(int i=1; i<A.length; i++){
            if( Math.abs(preSum - postSum) < min ){
                min = Math.abs(preSum - postSum);
            }
            preSum += A[i];
            postSum -= A[i];
        }

        return min;
    }
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N)

expand all Example tests

▶

example
example test

✔

0.004 s

expand all Correctness tests

▶

double
two elements

✔

0.012 s

0.008 s

▶

simple_positive
simple test with positive numbers, length = 5

✔

0.004 s

0.008 s

▶

simple_negative
simple test with negative numbers, length = 5

✔

0.008 s

▶

simple_boundary
only one element on one of the sides

✔

0.008 s

0.004 s

0.008 s

▶

small_random
random small, length = 100

✔

0.004 s

▶

small_range
range sequence, length = ~1,000

✔

0.008 s

▶

small
small elements

✔

0.008 s

expand all Performance tests

▶

medium_random1
random medium, numbers from 0 to 100, length = ~10,000

✔

0.024 s

▶

medium_random2
random medium, numbers from -1,000 to 50, length = ~10,000

✔

0.028 s

▶

large_ones
large sequence, numbers from -1 to 1, length = ~100,000

✔

0.164 s

0.168 s

▶

large_random
random large, length = ~100,000

✔

0.212 s

▶

large_sequence
large sequence, length = ~100,000

✔

0.100 s

▶

large_extreme
large test with maximal and minimal values, length = ~100,000

✔

0.236 s

0.240 s

0.192 s