Maximum Product Subarray - Using Two Traversals in C++

In this problem, we are given an array arr[] of integers. Our task is to create a program to find the Maximum Product Subarray - Using Two Traversals in C++.

Problem description − Here in the array, we will find the maximum product subarray using two traversals one from index 0 and another index (n-1).

Let’s take an example to understand the problem,

Input

arr[] = {4, -2, 5, -6, 0, 8}

Output

240

Example

Subarray = {4, -2, 5, -6}
Maximum product = 4 * (-2) * 5 * (-6) = 240

Solution Approach

To solve this problem using two traversals. Here, we will find the maximum product using two local maximum values for traversal from left to right i.e. from index 0 to n-1. And one for traversal from right to left i.e. from index n-1 to 0. The rest algorithm is the same as finding the maximum product subarray.

Program to illustrate the working of our solution,

Example

 Live Demo

#include<iostream>
using namespace std;
int CalcMaxProductSubArray(int arr[], int n) {
   int frntMax = 1, rearMax = 1, maxVal = 1;
   for (int i=0; i<n; i++) {
      frntMax = frntMax*arr[i];
      if (frntMax == 0)
         frntMax = 1;
   }
   for (int i=n-1; i>=0; i--) {
      rearMax = rearMax * arr[i];
      if (rearMax == 0)
         rearMax = 1;
   }
   maxVal = max(frntMax, rearMax);
   return maxVal;
}
int main() {
   int arr[] = {4, -2, 5, -6, 0, 8};
   int n = sizeof(arr)/sizeof(arr[0]);
   cout<<"Maximum product subarray is "<<CalcMaxProductSubArray(arr, n);
   return 0;
}

Output

Maximum product subarray is 240

Ayush Gupta

Published on 03-Jul-2020 07:49:14

• Related Questions & Answers
• Maximum Product Subarray | Added negative product case in C++
• Maximum Product Subarray in Python
• Collect maximum points in a grid using two traversals
• Maximum length subarray with LCM equal to product in C++
• Program to find maximum product of contiguous subarray in Python
• Subarray Product Less Than K in C++
• Maximum Sum SubArray using Divide and Conquer in C++
• Maximum Subarray Sum after inverting at most two elements in C++
• Maximum Sum Circular Subarray in C++
• Maximum Average Subarray I in C++
• Maximum sum bitonic subarray in C++
• Maximum Average Subarray II in C++
• Maximum Subarray Sum using Divide and Conquer algorithm in C++
• Maximum Subarray in Python
• Delete an element from array using two traversals and one traversal in C++?