Highest product of triplets of a given list of integers

highest-product-of-triplets.clj

;; Clojure 

(defn highest-product-of-triplets [g]
  "returns the highest product of 3 from given `list of integers` g"
  (if (count g) > 2)
  (let [sorted (sort g)
        triplets (partition 3 1 sorted)
        max-triplet (last triplets) 
        min-triplet  (first triplets) 
        negatives (filter #(> 0 %) min-triplet)]  
    
    (if (and (> (count negatives) 1) ;; atleast 2 negatives to make a positive 
             (< (apply max max-triplet) (abs (apply * negatives))))
      
      (let [[a b] min-triplet]  
        
        (* (last max-triplet) (apply max (map * [a b] [b a]))
           
           ))
      
      ;; Not enough negative integers found
      ;; (reduce * (take 3 (reverse  (sort g))))
      (reduce * (take 3 (reverse  sorted)))
      
      )))


(def a '(-1, 2, 3, -5, -6, 7, 11, 4))
(def b '(-1, 1, -20, 600, 15, 15))
(def c  '(1, 10, 2, 6, 5, 3))

(highest-product-of-triplets a) ;; 330
(highest-product-of-triplets b) ;; => 135000
(highest-product-of-triplets c) ;; => 300

highest-product-of-triplets.cljs

;; Clojurescript

(defn highest-product-of-triplets [g]
  "returns the highest product of 3 from given `list of integers` g"
  (if (count g) > 2)
  (let [sorted (sort g)
        triplets (partition 3 1 sorted)
        max-triplet (last triplets) 
        min-triplet  (first triplets) 
        negatives (filter #(> 0 %) min-triplet)]  
    
    (if (and (> (count negatives) 1) ;; atleast 2 negatives to make a positive 
             (< (apply max max-triplet) (js/Math.abs (apply * negatives))))
      
      (let [[a b] min-triplet]  
        
        (* (last max-triplet) (apply max (map * [a b] [b a]))
           
           ))
      
      ;; Not enough negative integers found
      ;; (reduce * (take 3 (reverse  (sort g))))
      (reduce * (take 3 (reverse  sorted)))
      
      )))


(def a '(-1, 2, 3, -5, -6, 7, 11, 4))
(def b '(-1, 1, -20, 600, 15, 15))
(def c  '(1, 10, 2, 6, 5, 3))

(highest-product-of-triplets a) ;; 330
(highest-product-of-triplets b) ;; => 135000
(highest-product-of-triplets c) ;; => 300

Main.java

package org.example;

public class Main {

        // Only using java.lang package Math.max(int, int) & Math.min(int, int) methods
        public static int highestProductOfTriplets(int[] nums) {
            if (nums.length < 3 ) {
                throw new IllegalArgumentException("Array must contain at least 3 integers");
            }

            // Initialize variables to track highest and lowest values
            int highest = Math.max(nums[0], nums[1]);
            int lowest = Math.min(nums[0], nums[1]);
            int highestProductOf2 = nums[0] * nums[1];
            int lowestProductOf2 = nums[0] * nums[1];
            int highestProductOf3 = nums[0] * nums[1] * nums[2];

            // Iterate through the array, updating variables as needed
            for (int i = 2; i < nums.length; i++) {
                int current = nums[i];

                highestProductOf3 = Math.max(highestProductOf3,
                        Math.max(current * highestProductOf2, current * lowestProductOf2));
                highestProductOf2 = Math.max(highestProductOf2,
                        Math.max(current * highest, current * lowest));
                lowestProductOf2 = Math.min(lowestProductOf2,
                        Math.min(current * highest, current * lowest));
                highest = Math.max(highest, current);
                lowest = Math.min(lowest, current);
            }

            return highestProductOf3;
        }

        public static void main(String[] args) {
            int[] nums1 = {1, 10, 2, 6, 5, 3}; // 300
            int [] nums2 = { 100, -10, -20, 600, 15, 15, 15 , 20, 600 }; // 36000000
            int [] nums3 = {-1, -1, -20, 600, 15, 15}; // 135000
            int [] nums4 = {-1, 2, 3, -5, -6, 7, 11, 4}; // 330
            int [] nums5 = {10, 10, 20, 6, -15, -15, -15 , 2, 6,6,15}; // 4500
            int [] nums6 =  {200, 31, 422, 5, 1, 0, 45}; // 3798000

            int result = highestProductOfTriplets (nums1);
            System.out.println(result); // 300

        }
}