A non-empty zero-indexed array A consisting of N integers is given.

A triplet (X, Y, Z), such that 0 ≤ X < Y < Z < N, is called a double slice.

The sum of double slice (X, Y, Z) is the total of A[X + 1] + A[X + 2] + ... + A[Y − 1] + A[Y + 1] + A[Y + 2] + ... + A[Z − 1].

For example, array A such that:

contains the following example double slices:

• double slice (0, 3, 6), sum is 2 + 6 + 4 + 5 = 17,
• double slice (0, 3, 7), sum is 2 + 6 + 4 + 5 − 1 = 16,
• double slice (3, 4, 5), sum is 0.

The goal is to find the maximal sum of any double slice.

Write a function:

class Solution { public int solution(int[] A); }

that, given a non-empty zero-indexed array A consisting of N integers, returns the maximal sum of any double slice.

For example, given:

the function should return 17, because no double slice of array A has a sum of greater than 17.

Assume that:

• N is an integer within the range [3..100,000];
• each element of array A is an integer within the range [−10,000..10,000].

Complexity:

• expected worst-case time complexity is O(N);
• expected worst-case space complexity is O(N), beyond input storage (not counting the storage required for input arguments).

Elements of input arrays can be modified.

// 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");import java.lang.Math;class Solution {    public int solution(int[] A) {        // write your code in Java SE 8        if(A.length < 4)            return 0;        int maxleft=0, maxending=0, maxslice=0;        for(int i=3; i<A.length; i++) {            maxleft = Math.max(maxleft+A[i-2], A[i-2]);            maxending = Math.max(maxleft, Math.max( A[i-1], maxending+A[i-1]));            maxslice = Math.max(maxending, maxslice);        }        return maxslice;    }}


https://codility.com/demo/results/trainingEJXAE5-H5P/