Tasks Details
easy
Minimize the value |(A[0] + ... + A[P-1]) - (A[P] + ... + A[N-1])|.
Task Score
50%
Correctness
100%
Performance
0%
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] = 3We 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] = 3the 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].
Copyright 2009–2025 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.
Solution
Programming language used Java 8
Time spent on task 24 minutes
Notes
not defined yet
Code: 16:56:52 UTC,
java,
verify,
result: Failed
// 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) {
List splittedTape = new ArrayList();
for (int i = 1; i < A.lenght; i++){
splittedTape.add(calculateDifference(i));
}
Collections.sort(splittedTape);
return splittedTape.get(0);
}
private int calculateDifference(int position, int[] array){
int sumA = 0;
int sumB = 0;
for (int i = 0; i < array.length; i++){
if (i < position){
sumA += array[i];
} else {
sumB += array[i];
}
}
return Math.abs(sumA - sumB);
}
}
Analysis
Compile error
Solution.java:10: error: cannot find symbol
for (int i = 1; i < A.lenght; i++){
^
symbol: variable lenght
location: variable A of type int[]
Solution.java:11: error: method calculateDifference in class Solution cannot be applied to given types;
splittedTape.add(calculateDifference(i));
^
required: int,int[]
found: int
reason: actual and formal argument lists differ in length
Solution.java:14: error: incompatible types: Object cannot be converted to int
return splittedTape.get(0);
^
Note: Solution.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
3 errors
Code: 16:57:26 UTC,
java,
verify,
result: Failed
// 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) {
List splittedTape = new ArrayList();
for (int i = 1; i < A.length; i++){
splittedTape.add(calculateDifference(i));
}
Collections.sort(splittedTape);
return splittedTape.get(0);
}
private int calculateDifference(int position, int[] array){
int sumA = 0;
int sumB = 0;
for (int i = 0; i < array.length; i++){
if (i < position){
sumA += array[i];
} else {
sumB += array[i];
}
}
return Math.abs(sumA - sumB);
}
}
Analysis
Compile error
Solution.java:11: error: method calculateDifference in class Solution cannot be applied to given types;
splittedTape.add(calculateDifference(i));
^
required: int,int[]
found: int
reason: actual and formal argument lists differ in length
Solution.java:14: error: incompatible types: Object cannot be converted to int
return splittedTape.get(0);
^
Note: Solution.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
2 errors
Code: 16:57:57 UTC,
java,
verify,
result: Failed
// 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) {
List<int> splittedTape = new ArrayList<int>();
for (int i = 1; i < A.length; i++){
splittedTape.add(calculateDifference(i));
}
Collections.sort(splittedTape);
return splittedTape.get(0);
}
private int calculateDifference(int position, int[] array){
int sumA = 0;
int sumB = 0;
for (int i = 0; i < array.length; i++){
if (i < position){
sumA += array[i];
} else {
sumB += array[i];
}
}
return Math.abs(sumA - sumB);
}
}
Analysis
Compile error
Solution.java:9: error: unexpected type
List<int> splittedTape = new ArrayList<int>();
^
required: reference
found: int
Solution.java:9: error: unexpected type
List<int> splittedTape = new ArrayList<int>();
^
required: reference
found: int
Solution.java:11: error: method calculateDifference in class Solution cannot be applied to given types;
splittedTape.add(calculateDifference(i));
^
required: int,int[]
found: int
reason: actual and formal argument lists differ in length
3 errors
Code: 16:58:19 UTC,
java,
verify,
result: Failed
// 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) {
List<int> splittedTape = new ArrayList<int>();
for (int i = 1; i < A.length; i++){
splittedTape.add(calculateDifference(i, A));
}
Collections.sort(splittedTape);
return splittedTape.get(0);
}
private int calculateDifference(int position, int[] array){
int sumA = 0;
int sumB = 0;
for (int i = 0; i < array.length; i++){
if (i < position){
sumA += array[i];
} else {
sumB += array[i];
}
}
return Math.abs(sumA - sumB);
}
}
Analysis
Compile error
Solution.java:9: error: unexpected type
List<int> splittedTape = new ArrayList<int>();
^
required: reference
found: int
Solution.java:9: error: unexpected type
List<int> splittedTape = new ArrayList<int>();
^
required: reference
found: int
2 errors
Code: 16:58:48 UTC,
java,
verify,
result: Passed
// 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) {
List<Integer> splittedTape = new ArrayList<Integer>();
for (int i = 1; i < A.length; i++){
splittedTape.add(calculateDifference(i, A));
}
Collections.sort(splittedTape);
return splittedTape.get(0);
}
private int calculateDifference(int position, int[] array){
int sumA = 0;
int sumB = 0;
for (int i = 0; i < array.length; i++){
if (i < position){
sumA += array[i];
} else {
sumB += array[i];
}
}
return Math.abs(sumA - sumB);
}
}
Analysis
Code: 17:05:25 UTC,
java,
verify,
result: Passed
// 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) {
List<Integer> splittedTape = new ArrayList<Integer>();
for (int i = 1; i < A.length; i++){
splittedTape.add(calculateDifference(i, A));
}
Collections.sort(splittedTape);
return splittedTape.get(0);
}
private int calculateDifference(int position, int[] array){
int sumA = 0;
int sumB = 0;
for (int i = 0; i < array.length; i++){
if (i < position){
sumA += array[i];
} else {
sumB += array[i];
}
}
return Math.abs(sumA - sumB);
}
}
Analysis
Code: 17:05:33 UTC,
java,
final,
score:
50
// 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) {
List<Integer> splittedTape = new ArrayList<Integer>();
for (int i = 1; i < A.length; i++){
splittedTape.add(calculateDifference(i, A));
}
Collections.sort(splittedTape);
return splittedTape.get(0);
}
private int calculateDifference(int position, int[] array){
int sumA = 0;
int sumB = 0;
for (int i = 0; i < array.length; i++){
if (i < position){
sumA += array[i];
} else {
sumB += array[i];
}
}
return Math.abs(sumA - sumB);
}
}Analysis summary
The following issues have been detected: timeout errors.
Analysis
Detected time complexity:
O(N * N)
expand all
Correctness tests
1.
1.272 s
OK
2.
1.365 s
OK
1.
1.368 s
OK
1.
1.360 s
OK
1.
1.370 s
OK
1.
1.385 s
OK
1.
1.369 s
OK
expand all
Performance tests
medium_random1
random medium, numbers from 0 to 100, length = ~10,000
random medium, numbers from 0 to 100, length = ~10,000
✘
TIMEOUT ERROR
running time: 3.31 sec., time limit: 2.51 sec.
running time: 3.31 sec., time limit: 2.51 sec.
1.
3.306 s
TIMEOUT ERROR,
running time: 3.31 sec., time limit: 2.51 sec.
medium_random2
random medium, numbers from -1,000 to 50, length = ~10,000
random medium, numbers from -1,000 to 50, length = ~10,000
✘
TIMEOUT ERROR
running time: 3.33 sec., time limit: 2.54 sec.
running time: 3.33 sec., time limit: 2.54 sec.
1.
3.326 s
TIMEOUT ERROR,
running time: 3.33 sec., time limit: 2.54 sec.
large_ones
large sequence, numbers from -1 to 1, length = ~100,000
large sequence, numbers from -1 to 1, length = ~100,000
✘
TIMEOUT ERROR
running time: >9.00 sec., time limit: 3.13 sec.
running time: >9.00 sec., time limit: 3.13 sec.
1.
9.000 s
TIMEOUT ERROR,
running time: >9.00 sec., time limit: 3.13 sec.
2.
9.000 s
TIMEOUT ERROR,
running time: >9.00 sec., time limit: 3.08 sec.
large_random
random large, length = ~100,000
random large, length = ~100,000
✘
TIMEOUT ERROR
running time: >9.00 sec., time limit: 3.30 sec.
running time: >9.00 sec., time limit: 3.30 sec.
1.
9.000 s
TIMEOUT ERROR,
running time: >9.00 sec., time limit: 3.30 sec.
2.
9.000 s
TIMEOUT ERROR,
running time: >9.00 sec., time limit: 3.28 sec.
large_sequence
large sequence, length = ~100,000
large sequence, length = ~100,000
✘
TIMEOUT ERROR
running time: >8.00 sec., time limit: 2.86 sec.
running time: >8.00 sec., time limit: 2.86 sec.
1.
8.000 s
TIMEOUT ERROR,
running time: >8.00 sec., time limit: 2.86 sec.
large_extreme
large test with maximal and minimal values, length = ~100,000
large test with maximal and minimal values, length = ~100,000
✘
TIMEOUT ERROR
running time: >9.00 sec., time limit: 3.38 sec.
running time: >9.00 sec., time limit: 3.38 sec.
1.
9.000 s
TIMEOUT ERROR,
running time: >9.00 sec., time limit: 3.38 sec.
2.
7.000 s
TIMEOUT ERROR,
running time: >7.00 sec., time limit: 1.99 sec.
3.
9.000 s
TIMEOUT ERROR,
running time: >9.00 sec., time limit: 3.21 sec.