# Maximum element in an array such that its previous and next element product is maximum

Given an array **arr[]** of **N** integers, the task is to print the largest element among the array such that its previous and next element product is maximum.**Examples:**

Input:arr[] = {5, 6, 4, 3, 2}Output:6

The product of the next and the previous elements

for every element of the given array are:

5 -> 2 * 6 = 12

6 -> 5 * 4 = 20

4 -> 6 * 3 = 18

3 -> 4 * 2 = 8

2 -> 3 * 5 = 15

Out of these 20 is the maximum.

Hence, 6 is the answer.Input:arr[] = {9, 2, 3, 1, 5, 17}Output:17

**Approach:** For every element of the array, find the product of its previous and next element. The element which has the maximum product is the result. If two elements have an equal product of next and previous elements then choose the greater element among them.

Below is the implementation of the above approach:

## C++

`#include<bits/stdc++.h>` `using` `namespace` `std;` `// Function to return the largest element` `// such that its previous and next` `// element product is maximum` `int` `maxElement(` `int` `a[], ` `int` `n)` `{` ` ` `if` `(n < 3)` ` ` `return` `-1;` ` ` `int` `maxElement = a[0];` ` ` `int` `maxProd = a[n - 1] * a[1];` ` ` `for` `(` `int` `i = 1; i < n; i++)` ` ` `{` ` ` `// Calculate the product of the previous` ` ` `// and the next element for` ` ` `// the current element` ` ` `int` `currProd = a[i - 1] * a[(i + 1) % n];` ` ` `// Update the maximum product` ` ` `if` `(currProd > maxProd)` ` ` `{` ` ` `maxProd = currProd;` ` ` `maxElement = a[i];` ` ` `}` ` ` `// If current product is equal to the` ` ` `// current maximum product then` ` ` `// choose the maximum element` ` ` `else` `if` `(currProd == maxProd)` ` ` `{` ` ` `maxElement = max(maxElement, a[i]);` ` ` `}` ` ` `}` ` ` `return` `maxElement;` `}` `// Driver code` `int` `main()` `{` ` ` `int` `a[] = { 5, 6, 4, 3, 2};` ` ` `int` `n = ` `sizeof` `(a)/` `sizeof` `(a[0]);` ` ` `cout << maxElement(a, n);` ` ` `return` `0;` `}` ` ` |

## Java

`// Java implementation of the approach` `class` `GFG {` ` ` `// Function to return the largest element` ` ` `// such that its previous and next` ` ` `// element product is maximum` ` ` `static` `int` `maxElement(` `int` `a[], ` `int` `n)` ` ` `{` ` ` `if` `(n < ` `3` `)` ` ` `return` `-` `1` `;` ` ` `int` `maxElement = a[` `0` `];` ` ` `int` `maxProd = a[n - ` `1` `] * a[` `1` `];` ` ` `for` `(` `int` `i = ` `1` `; i < n; i++) {` ` ` `// Calculate the product of the previous` ` ` `// and the next element for` ` ` `// the current element` ` ` `int` `currProd = a[i - ` `1` `] * a[(i + ` `1` `) % n];` ` ` `// Update the maximum product` ` ` `if` `(currProd > maxProd) {` ` ` `maxProd = currProd;` ` ` `maxElement = a[i];` ` ` `}` ` ` `// If current product is equal to the` ` ` `// current maximum product then` ` ` `// choose the maximum element` ` ` `else` `if` `(currProd == maxProd) {` ` ` `maxElement = Math.max(maxElement, a[i]);` ` ` `}` ` ` `}` ` ` `return` `maxElement;` ` ` `}` ` ` `// Driver code` ` ` `public` `static` `void` `main(String[] args)` ` ` `{` ` ` `int` `[] a = { ` `5` `, ` `6` `, ` `4` `, ` `3` `, ` `2` `};` ` ` `int` `n = a.length;` ` ` `System.out.println(maxElement(a, n));` ` ` `}` `}` |

## Python3

`# Function to return the largest element` `# such that its previous and next` `# element product is maximum` `def` `maxElement(a, n):` ` ` `if` `n < ` `3` `:` ` ` `return` `-` `1` ` ` `maxElement ` `=` `a[` `0` `]` ` ` `maxProd ` `=` `a[n ` `-` `1` `] ` `*` `a[` `1` `]` ` ` `for` `i ` `in` `range` `(` `1` `, n):` ` ` ` ` `# Calculate the product of the previous` ` ` `# and the next element for` ` ` `# the current element` ` ` `currprod ` `=` `a[i ` `-` `1` `] ` `*` `a[(i ` `+` `1` `) ` `%` `n]` ` ` `if` `currprod > maxProd:` ` ` `maxProd ` `=` `currprod` ` ` `maxElement ` `=` `a[i]` ` ` ` ` `# If current product is equal to the` ` ` `# current maximum product then` ` ` `# choose the maximum element` ` ` `elif` `currprod ` `=` `=` `maxProd:` ` ` `maxElement ` `=` `max` `(maxElement, a[i])` ` ` `return` `maxElement` `# Driver code` `a ` `=` `[` `5` `, ` `6` `, ` `4` `, ` `3` `, ` `2` `]` `n ` `=` `len` `(a)` `#sizeof(a[0])` `print` `(maxElement(a, n))` `# This code is contributed by mohit kumar 29` |

## C#

`// C# implementation of the approach` `using` `System;` `class` `GFG` `{` ` ` `// Function to return the largest element` ` ` `// such that its previous and next` ` ` `// element product is maximum` ` ` `static` `int` `maxElement(` `int` `[]a, ` `int` `n)` ` ` `{` ` ` `if` `(n < 3)` ` ` `return` `-1;` ` ` `int` `maxElement = a[0];` ` ` `int` `maxProd = a[n - 1] * a[1];` ` ` `for` `(` `int` `i = 1; i < n; i++)` ` ` `{` ` ` `// Calculate the product of the previous` ` ` `// and the next element for` ` ` `// the current element` ` ` `int` `currProd = a[i - 1] * a[(i + 1) % n];` ` ` `// Update the maximum product` ` ` `if` `(currProd > maxProd)` ` ` `{` ` ` `maxProd = currProd;` ` ` `maxElement = a[i];` ` ` `}` ` ` `// If current product is equal to the` ` ` `// current maximum product then` ` ` `// choose the maximum element` ` ` `else` `if` `(currProd == maxProd)` ` ` `{` ` ` `maxElement = Math.Max(maxElement, a[i]);` ` ` `}` ` ` `}` ` ` `return` `maxElement;` ` ` `}` ` ` `// Driver code` ` ` `public` `static` `void` `Main()` ` ` `{` ` ` `int` `[] a = { 5, 6, 4, 3, 2 };` ` ` `int` `n = a.Length;` ` ` `Console.WriteLine(maxElement(a, n));` ` ` `}` `}` `// This code is contributed by AnkitRai01` |

## Javascript

`<script>` `// Java script implementation of the approach` ` ` `// Function to return the largest element` ` ` `// such that its previous and next` ` ` `// element product is maximum` ` ` `function` `maxElement(a,n)` ` ` `{` ` ` `if` `(n < 3)` ` ` `return` `-1;` ` ` `let maxElement = a[0];` ` ` `let maxProd = a[n - 1] * a[1];` ` ` `for` `(let i = 1; i < n; i++) {` ` ` `// Calculate the product of the previous` ` ` `// and the next element for` ` ` `// the current element` ` ` `let currProd = a[i - 1] * a[(i + 1) % n];` ` ` `// Update the maximum product` ` ` `if` `(currProd > maxProd) {` ` ` `maxProd = currProd;` ` ` `maxElement = a[i];` ` ` `}` ` ` `// If current product is equal to the` ` ` `// current maximum product then` ` ` `// choose the maximum element` ` ` `else` `if` `(currProd == maxProd) {` ` ` `maxElement = Math.max(maxElement, a[i]);` ` ` `}` ` ` `}` ` ` `return` `maxElement;` ` ` `}` ` ` `// Driver code ` ` ` `let a = [ 5, 6, 4, 3, 2 ];` ` ` `let n = a.length;` ` ` `document.write(maxElement(a, n));` ` ` `// This code is contributed by sravan kumar G` `</script>` |

**Output:**

6

**Time Complexity :** O(n)**Auxiliary Space :** O(1)