Tasks Details
easy
Minimize the value |(A[0] + ... + A[P-1]) - (A[P] + ... + A[N-1])|.
Task Score
84%
Correctness
71%
Performance
100%
Task description
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 18 minutes
Notes
not defined yet
Code: 07:49:07 UTC,
java,
autosave
Code: 08:05:52 UTC,
java,
autosave
// 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) {
int totalSum = IntStream.of(A).sum();
int frontSum = 0;
int backSum = 0;
int minimumDiff = Integer.MAX_VALUE;
for (int i=0; i<A.length; i++) {
frontSum += A[i];
backSum = totalSum - frontSum;
minimumDiff = Math.min(minimumDiff, Math.abs(frontSum-backSum));
}
return minimumDiff;
}
}
Code: 08:06:12 UTC,
java,
autosave
// you can also use imports, for example:
// import java.util.*;
import java.util.stream.IntStream;
// 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) {
int totalSum = IntStream.of(A).sum();
int frontSum = 0;
int backSum = 0;
int minimumDiff = Integer.MAX_VALUE;
for (int i=0; i<A.length; i++) {
frontSum += A[i];
backSum = totalSum - frontSum;
minimumDiff = Math.min(minimumDiff, Math.abs(frontSum-backSum));
}
return minimumDiff;
}
}
Code: 08:06:38 UTC,
java,
verify,
result: Passed
// you can also use imports, for example:
// import java.util.*;
import java.util.stream.IntStream;
// 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) {
int totalSum = IntStream.of(A).sum();
int frontSum = 0;
int backSum = 0;
int minimumDiff = Integer.MAX_VALUE;
for (int i=0; i<A.length; i++) {
frontSum += A[i];
backSum = totalSum - frontSum;
minimumDiff = Math.min(minimumDiff, Math.abs(frontSum-backSum));
}
return minimumDiff;
}
}
User test case 1:
[3, 5, 2, 4, -1000, -531]
User test case 2:
[-1000, 1000]
User test case 3:
[0, 0, 2, 1, 56, 89]
User test case 4:
[999, 998, -999, -222, 55, 4, 3]
Analysis
expand all
User tests
1.
0.092 s
OK
function result: 455
function result: 455
1.
0.092 s
OK
function result: 0
function result: 0
1.
0.088 s
OK
function result: 30
function result: 30
1.
0.088 s
OK
function result: 714
function result: 714
Code: 08:06:45 UTC,
java,
verify,
result: Passed
// you can also use imports, for example:
// import java.util.*;
import java.util.stream.IntStream;
// 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) {
int totalSum = IntStream.of(A).sum();
int frontSum = 0;
int backSum = 0;
int minimumDiff = Integer.MAX_VALUE;
for (int i=0; i<A.length; i++) {
frontSum += A[i];
backSum = totalSum - frontSum;
minimumDiff = Math.min(minimumDiff, Math.abs(frontSum-backSum));
}
return minimumDiff;
}
}
User test case 1:
[3, 5, 2, 4, -1000, -531]
User test case 2:
[-1000, 1000]
User test case 3:
[0, 0, 2, 1, 56, 89]
User test case 4:
[999, 998, -999, -222, 55, 4, 3]
Analysis
expand all
User tests
1.
0.092 s
OK
function result: 455
function result: 455
1.
0.088 s
OK
function result: 0
function result: 0
1.
0.092 s
OK
function result: 30
function result: 30
1.
0.092 s
OK
function result: 714
function result: 714
Code: 08:06:50 UTC,
java,
final,
score:
84
// you can also use imports, for example:
// import java.util.*;
import java.util.stream.IntStream;
// 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) {
int totalSum = IntStream.of(A).sum();
int frontSum = 0;
int backSum = 0;
int minimumDiff = Integer.MAX_VALUE;
for (int i=0; i<A.length; i++) {
frontSum += A[i];
backSum = totalSum - frontSum;
minimumDiff = Math.min(minimumDiff, Math.abs(frontSum-backSum));
}
return minimumDiff;
}
}
Analysis summary
The following issues have been detected: wrong answers.
For example, for the input [-1000, 1000] the solution returned a wrong answer (got 0 expected 2000).
Analysis
Detected time complexity:
O(N)
expand all
Correctness tests
1.
0.088 s
WRONG ANSWER,
got 0 expected 2000
2.
0.088 s
OK
3.
0.088 s
OK
1.
0.088 s
OK
2.
0.088 s
OK
1.
0.088 s
OK
2.
0.088 s
OK
1.
0.088 s
OK
2.
0.088 s
OK
3.
0.088 s
OK
4.
0.088 s
OK
1.
0.088 s
OK
1.
0.092 s
OK
1.
0.088 s
WRONG ANSWER,
got 0 expected 20
expand all
Performance tests
1.
0.104 s
OK
1.
0.108 s
OK
1.
0.276 s
OK
2.
0.276 s
OK
1.
0.320 s
OK
2.
0.320 s
OK
1.
0.192 s
OK
1.
0.340 s
OK
2.
0.348 s
OK
3.
0.292 s
OK