MaxSliceSum at app.codility.com/programmers in JavaScript Explained: Find a maximum sum of a compact subsequence of array elements.
Task score : 100% - Correctness : 100% ; Performance : 100%
Detected time complexity : O(N)
Lesson 9 at app.codility.com/programmers
The solution and its explanation are given below.
Category of Article : Technology | Computers and Software | Algorithm
By: Chrysanthus Date Published: 30 Jul 2025
Problem
A non-empty array A consisting of N integers is given. A pair of integers (P, Q), such that 0 ≤ P ≤ Q < N, is called a slice of array A. The sum of a slice (P, Q) is the total of A[P] + A[P+1] + ... + A[Q].Write a function:
function solution(A);that, given an array A consisting of N integers, returns the maximum sum of any slice of A.
For example, given array A such that:
A[0] = 3 A[1] = 2 A[2] = -6
A[3] = 4 A[4] = 0
the function should return 5 because:
<script type='text/javascript'>
"use strict";
function solution(A) {
let N = A.length;
let prevMaxSum = A[0];
let accumulatingMaxSum = A[0];
for (let i=1; i < N; i++) {
let tempRunTotal = accumulatingMaxSum + A[i]; //could be smaller than A[i]
if (A[i] > tempRunTotal)
accumulatingMaxSum = A[i]; //elements start rising
else
accumulatingMaxSum = tempRunTotal; //continue to accumulate
if (accumulatingMaxSum > prevMaxSum) //comparing all the maximum sums
prevMaxSum = accumulatingMaxSum;
}
return prevMaxSum;
}
const A = [5, -7, 3, 5, -2, 4, -1]; // {3, 5, -2, 4} -> 10
let ret1 = solution(A);
document.write(ret1 + '<br>');
const B = [-2, 1, -3, 4, -1, 2, 1, -5, 4]; // {4, −1, 2, 1} -> 6
let ret2 = solution(B);
document.write(ret2 + '<br>');
const C = [3, 2, -6, 4, 0]; //{3, 2} -> 5
let ret3 = solution(C);
document.write(ret3 + '<br>');
const D = [3, 2, 6, -1, 4, 5, -1, 2]; //{3, 2, 6, -1, 4, 5, -1, 2} -> 20
let ret4 = solution(D);
document.write(ret4 + '<br>');
const E = [5, 7, -4, -10, -6, 6, 5, 10, -5, 15, 4, -8, -15, -22]; // {6, 5, 10, -5, 15, 4}->35
let ret5 = solution(E);
document.write(ret5 + '<br>');
const F = [-4, 10, 15, 9, -5, -20, -3, -12, -3, 4, 6, 3, 2, 8, 3, -5, -2]; // {10, 15, 9}->34
let ret6 = solution(F);
document.write(ret6 + '<br>');
</script>
The output is:10
6
5
20
35
34
At app.codility.com/programmers the scoring and detected time complexity for this solution() is:
Task score : 100% - Correctness : 100% ; Performance : 100%
Detected time complexity : O(N)
Thanks for reading.