Test results - Codility

Tasks Details

easy

1. TapeEquilibrium

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

Task Score

66%

Correctness

100%

Performance

33%

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 C#

Time spent on task 10 minutes

Notes

not defined yet

Code: 11:45:38 UTC, c, verify, result: Failed

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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 4.8.2)
    
    
    		int min = -1;
		
		for(int i = 1; i < A.Length; i++)
		{
			int totalFormer = 0;
			int totalAfter = 0;
			int dif = 0;

			for(int j = 0; j < i; j++)
			{
				totalFormer += A[j];
			}

			for(int j = i; j < A.Length; j++)
			{
				totalAfter += A[j];
			}
			
			dif = System.Math.Abs (totalFormer - totalAfter);
			
			if(min < 0 || dif < min) min = dif;
		}
		
		return min;

}

Analysis

Compile error

func.c: In function 'solution':
func.c:10:23: error: request for member 'Length' in something not a structure or union
   for(int i = 1; i < A.Length; i++)
                       ^
func.c:21:24: error: request for member 'Length' in something not a structure or union
    for(int j = i; j < A.Length; j++)
                        ^
func.c:26:10: error: 'System' undeclared (first use in this function)
    dif = System.Math.Abs (totalFormer - totalAfter);
          ^
func.c:26:10: note: each undeclared identifier is reported only once for each function it appears in

Code: 11:45:57 UTC, cs, verify, result: Passed

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using System;
// you can also use other imports, for example:
// using System.Collections.Generic;

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

class Solution {
    public int solution(int[] A) {
        // write your code in C# 6.0 with .NET 4.5 (Mono)
        
        
        		int min = -1;
		
		for(int i = 1; i < A.Length; i++)
		{
			int totalFormer = 0;
			int totalAfter = 0;
			int dif = 0;

			for(int j = 0; j < i; j++)
			{
				totalFormer += A[j];
			}

			for(int j = i; j < A.Length; j++)
			{
				totalAfter += A[j];
			}
			
			dif = System.Math.Abs (totalFormer - totalAfter);
			
			if(min < 0 || dif < min) min = dif;
		}
		
		return min;

    }
}

Analysis

expand all Example tests

▶

example
example test

✔

0.053 s

Code: 11:48:33 UTC, cs, verify, result: Failed

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using System;

class Solution {
    public int solution(int[] A) {
        int min = -1;
		
		for(int i = 1; i < A.Length; i++)
		{
			int totalFormer = 0;
			int totalAfter = 0;
			int dif = 0;

			for(int j = 0; j < i; j++)
			{
				totalFormer += A[j];
			}

			totalAfter = (A.Sum() - totalFormer);
			
			dif = System.Math.Abs (totalFormer - totalAfter);
			
			if(min < 0 || dif < min) min = dif;
		}
		
		return min;
    }
}

Analysis

Compile error

Compilation failed: 1 error(s), 0 warnings
Solution.cs(18,20): error CS1061: Type `int[]' does not contain a definition for `Sum' and no extension method `Sum' of type `int[]' could be found. Are you missing `System.Linq' using directive?
/opt/lang/mono/lib/mono/4.5/mscorlib.dll (Location of the symbol related to previous error)

Code: 11:51:44 UTC, cs, verify, result: Passed

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using System;

class Solution {
    public int solution(int[] A) {
		
		int sum = 0;
		foreach (int a in A) {
			sum += a;
		}
		
        int min = -1;

		for(int i = 1; i < A.Length; i++)
		{
			int totalFormer = 0;
			int totalAfter = 0;
			int dif = 0;

			for(int j = 0; j < i; j++)
			{
				totalFormer += A[j];
			}

			totalAfter = (sum - totalFormer);
			
			dif = System.Math.Abs (totalFormer - totalAfter);
			
			if(min < 0 || dif < min) min = dif;
		}
		
		return min;
    }
}

Analysis

expand all Example tests

▶

example
example test

✔

0.035 s

Code: 11:54:24 UTC, cs, verify, result: Passed

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using System;

class Solution {
    public int solution(int[] A) {
		
		int sum = 0;
		foreach (int a in A) {
			sum += a;
		}

		int min = -1;

		for(int i = 1; i < A.Length; i++)
		{
			int sumFormer = 0;
			int sumAfter = 0;
			int dif = 0;

			for(int j = 0; j < i; j++)
			{
				sumFormer += A[j];
			}

			sumAfter = (sum - sumFormer);

			dif = System.Math.Abs (sumFormer - sumAfter);

			if(min < 0 || dif < min) min = dif;
		}

		return min;
    }
}

Analysis

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▶

example
example test

✔

0.032 s

Code: 11:54:31 UTC, cs, verify, result: Passed

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using System;

class Solution {
    public int solution(int[] A) {
		
		int sum = 0;
		foreach (int a in A) {
			sum += a;
		}

		int min = -1;

		for(int i = 1; i < A.Length; i++)
		{
			int sumFormer = 0;
			int sumAfter = 0;
			int dif = 0;

			for(int j = 0; j < i; j++)
			{
				sumFormer += A[j];
			}

			sumAfter = (sum - sumFormer);

			dif = System.Math.Abs (sumFormer - sumAfter);

			if(min < 0 || dif < min) min = dif;
		}

		return min;
    }
}

Analysis

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▶

example
example test

✔

0.032 s

Code: 11:54:36 UTC, cs, final, score: 66

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using System;

class Solution {
    public int solution(int[] A) {
		
		int sum = 0;
		foreach (int a in A) {
			sum += a;
		}

		int min = -1;

		for(int i = 1; i < A.Length; i++)
		{
			int sumFormer = 0;
			int sumAfter = 0;
			int dif = 0;

			for(int j = 0; j < i; j++)
			{
				sumFormer += A[j];
			}

			sumAfter = (sum - sumFormer);

			dif = System.Math.Abs (sumFormer - sumAfter);

			if(min < 0 || dif < min) min = dif;
		}

		return min;
    }
}

Analysis summary

The following issues have been detected: timeout errors.

Analysis

Detected time complexity:

O(N * N)

expand all Example tests

▶

example
example test

✔

0.051 s

expand all Correctness tests

▶

double
two elements

✔

0.053 s

0.052 s

▶

simple_positive
simple test with positive numbers, length = 5

✔

0.052 s

▶

simple_negative
simple test with negative numbers, length = 5

✔

0.054 s

▶

small_random
random small, length = 100

✔

0.052 s

▶

small_range
range sequence, length = ~1,000

✔

0.053 s

▶

small
small elements

✔

0.051 s

expand all Performance tests

▶

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

✔

0.099 s

▶

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

✔

0.100 s

▶

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

✘

TIMEOUT ERROR
running time: 4.52 sec., time limit: 0.30 sec.

4.516 s

TIMEOUT ERROR, running time: 4.52 sec., time limit: 0.30 sec.

4.522 s

TIMEOUT ERROR, running time: 4.52 sec., time limit: 0.30 sec.

▶

large_random
random large, length = ~100,000

✘

TIMEOUT ERROR
running time: 4.52 sec., time limit: 0.33 sec.

4.522 s

TIMEOUT ERROR, running time: 4.52 sec., time limit: 0.33 sec.

4.524 s

TIMEOUT ERROR, running time: 4.52 sec., time limit: 0.33 sec.

▶

large_sequence
large sequence, length = ~100,000

✘

TIMEOUT ERROR
running time: 1.18 sec., time limit: 0.26 sec.

1.176 s

TIMEOUT ERROR, running time: 1.18 sec., time limit: 0.26 sec.

▶

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

✘

TIMEOUT ERROR
running time: 4.52 sec., time limit: 0.33 sec.

4.524 s

TIMEOUT ERROR, running time: 4.52 sec., time limit: 0.33 sec.

4.528 s

TIMEOUT ERROR, running time: 4.53 sec., time limit: 0.33 sec.

2.917 s

TIMEOUT ERROR, running time: 2.92 sec., time limit: 0.31 sec.