Tasks Details
easy
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] = 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:
function solution(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 2009–2024 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.
Solution
Programming language used JavaScript
Time spent on task 2 minutes
Notes
not defined yet
Task timeline
Code: 13:55:57 UTC,
java,
autosave
Code: 13:55:57 UTC,
java,
autosave
Code: 13:56:07 UTC,
js,
autosave
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
// Get the total sum first.
let total = A.reduce((prevValue, currValue) => {
return prevValue + currValue;
}, 0);
let totalLeft = A[0];
let totalRight = total - A[0];
let minDiff = Math.abs(totalRight - totalLeft);
// console.log(totalLeft, totalRight, minDiff)
// Start from 1, cos P starts from index 1.
for(let i = 1; i < A.length - 1; ++i) {
let diff = Math.abs(totalLeft - totalRight);
minDiff = Math.min(minDiff, diff);
totalLeft += A[i];
totalRight -= A[i];
}
return minDiff;
}
Code: 13:56:11 UTC,
js,
verify,
result: Passed
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
// Get the total sum first.
let total = A.reduce((prevValue, currValue) => {
return prevValue + currValue;
}, 0);
let totalLeft = A[0];
let totalRight = total - A[0];
let minDiff = Math.abs(totalRight - totalLeft);
// console.log(totalLeft, totalRight, minDiff)
// Start from 1, cos P starts from index 1.
for(let i = 1; i < A.length - 1; ++i) {
totalLeft += A[i];
totalRight -= A[i];
let diff = Math.abs(totalLeft - totalRight);
minDiff = Math.min(minDiff, diff);
}
return minDiff;
}
Analysis
Code: 13:56:17 UTC,
js,
verify,
result: Passed
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
// Get the total sum first.
let total = A.reduce((prevValue, currValue) => {
return prevValue + currValue;
}, 0);
let totalLeft = A[0];
let totalRight = total - A[0];
let minDiff = Math.abs(totalRight - totalLeft);
// console.log(totalLeft, totalRight, minDiff)
// Start from 1, cos P starts from index 1.
for(let i = 1; i < A.length - 1; ++i) {
totalLeft += A[i];
totalRight -= A[i];
let diff = Math.abs(totalLeft - totalRight);
minDiff = Math.min(minDiff, diff);
}
return minDiff;
}
User test case 1:
[-1000, 1000]
Analysis
Code: 13:56:28 UTC,
js,
verify,
result: Passed
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
// Get the total sum first.
let total = A.reduce((prevValue, currValue) => {
return prevValue + currValue;
}, 0);
let totalLeft = A[0];
let totalRight = total - A[0];
let minDiff = Math.abs(totalRight - totalLeft);
// console.log(totalLeft, totalRight, minDiff)
// Start from 1, cos P starts from index 1.
for(let i = 1; i < A.length ; ++i) {
totalLeft += A[i];
totalRight -= A[i];
let diff = Math.abs(totalLeft - totalRight);
minDiff = Math.min(minDiff, diff);
}
return minDiff;
}
User test case 1:
[-1000, 1000]
Analysis
Code: 13:56:36 UTC,
js,
autosave
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
// Get the total sum first.
let total = A.reduce((prevValue, currValue) => {
return prevValue + currValue;
}, 0);
let totalLeft = A[0];
let totalRight = total - A[0];
let minDiff = Math.abs(totalRight - totalLeft);
// console.log(totalLeft, totalRight, minDiff)
// Start from 1, cos P starts from index 1.
for(let i = 1; i < A.length - 1; ++i) {
totalLeft += A[i];
totalRight -= A[i];
let diff = Math.abs(totalLeft - totalRight);
minDiff = Math.min(minDiff, diff);
}
return minDiff;
}
Code: 13:57:14 UTC,
js,
verify,
result: Passed
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
// Get the total sum first.
let total = A.reduce((prevValue, currValue) => {
return prevValue + currValue;
}, 0);
let totalLeft = A[0];
let totalRight = total - A[0];
let minDiff = Math.abs(totalRight - totalLeft);
// console.log(totalLeft, totalRight, minDiff)
// Start from 1, cos P starts from index 1.
for(let i = 1; i < A.length - 1; ++i) {
totalLeft += A[i];
totalRight -= A[i];
let diff = Math.abs(totalLeft - totalRight);
minDiff = Math.min(minDiff, diff);
}
return minDiff;
}
User test case 1:
[-1000, 1000]
Analysis
Code: 13:57:17 UTC,
js,
final,
score:
100
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
// Get the total sum first.
let total = A.reduce((prevValue, currValue) => {
return prevValue + currValue;
}, 0);
let totalLeft = A[0];
let totalRight = total - A[0];
let minDiff = Math.abs(totalRight - totalLeft);
// console.log(totalLeft, totalRight, minDiff)
// Start from 1, cos P starts from index 1.
for(let i = 1; i < A.length - 1; ++i) {
totalLeft += A[i];
totalRight -= A[i];
let diff = Math.abs(totalLeft - totalRight);
minDiff = Math.min(minDiff, diff);
}
return minDiff;
}Analysis summary
The solution obtained perfect score.
Analysis
Detected time complexity:
O(N)
expand all
Correctness tests
1.
0.076 s
OK
2.
0.076 s
OK
3.
0.076 s
OK
1.
0.076 s
OK
2.
0.080 s
OK
1.
0.076 s
OK
2.
0.080 s
OK
1.
0.076 s
OK
2.
0.076 s
OK
3.
0.076 s
OK
4.
0.076 s
OK
1.
0.076 s
OK
1.
0.080 s
OK
1.
0.076 s
OK
expand all
Performance tests
1.
0.088 s
OK
1.
0.088 s
OK
1.
0.112 s
OK
2.
0.116 s
OK
1.
0.120 s
OK
2.
0.120 s
OK
1.
0.104 s
OK
1.
0.120 s
OK
2.
0.124 s
OK
3.
0.116 s
OK