MaxProductOfThree.js

/*
  Sort A [a1..aN] where a1 <= aN. Then:
  Case 1: A=[+, +, ..., +] || A=[-, -, ..., -] => Max = Product of the last three elements
  Case 2: N= 3 => Only one product exists
  Case 3: A=[-, -, ...., +] => Max = Product of the first and the last two elements  
*/
function solution(A) {
    let N = A.length;
    A.sort((a,b) => (a-b));
    return Math.max(A[0] * A[1] * A[N - 1], A[N - 1] * A[N - 2] * A[N - 3]);
}