MaxProductOfThree

A non-empty array A consisting of N integers is given. The product of triplet (P, Q, R) equates to A[P] * A[Q] * A[R] (0 ≤ P < Q < R < N).

For example, array A such that:

A[0] = -3 A[1] = 1 A[2] = 2 A[3] = -2 A[4] = 5 A[5] = 6

contains the following example triplets:

• (0, 1, 2), product is −3 * 1 * 2 = −6
• (1, 2, 4), product is 1 * 2 * 5 = 10
• (2, 4, 5), product is 2 * 5 * 6 = 60

Your goal is to find the maximal product of any triplet.

Write a function:

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

that, given a non-empty array A, returns the value of the maximal product of any triplet.

For example, given array A such that:

A[0] = -3 A[1] = 1 A[2] = 2 A[3] = -2 A[4] = 5 A[5] = 6

the function should return 60, as the product of triplet (2, 4, 5) is maximal.

Write an efficient algorithm for the following assumptions:

• N is an integer within the range [3..100,000];
• each element of array A is an integer within the range [−1,000..1,000].

function solution(A) {
    // write your code in JavaScript (Node.js 8.9.4)

    A.sort((a, b) => a-b);
    let leng = A.length;
    let answer1 = A[leng-1]* A[leng-2] *A[leng-3];

    if(A[0] <= 0 && A[1]<= 0 && A[leng-1] >= 0) {
        let answer2 = A[0]*A[1]*A[leng-1];

        if(answer2 > answer1) {
            return answer2;
        }
    }
    return answer1;


}