Related Articles

# Maximum length of subarray such that all elements are equal in the subarray

• Difficulty Level : Basic
• Last Updated : 16 Apr, 2021

Given an array arr[] of N integers, the task is to find the maximum length subarray that contains similar elements.
Examples:

Input: arr[] = {1, 2, 3, 4, 5, 5, 5, 5, 5, 2, 2, 1, 1}
Output:
Explanation:
The subarray {5, 5, 5, 5, 5} has maximum length 5 with identical elements.
Input: arr[] = {1, 2, 3, 4}
Output:
Explanation:
All identical element subarray are {1}, {2}, {3}, and {4} which is of length 1.

Approach: The idea is to traverse the array store the maximum length and current length of the subarray which has the same elements. Below are the steps:

1. Traverse the array and check if the current element is equal to the next element then increase the value of the current length variable.
2. Now, compare the current length with max length to update the maximum length of the subarray.
3. If the current element is not equal to the next element then reset the length to 1 and continue this for all the elements of the array.

Below is the implementation of the above approach:

## C++

 `// C++ program for the above approach` `#include ``using` `namespace` `std;` `// Function to find the longest``// subarray with same element``int` `longest_subarray(``int` `arr[], ``int` `d)``{` `    ``int` `i = 0, j = 1, e = 0;` `    ``for` `(i = 0; i < d - 1; i++) {` `        ``// Check if the elements``        ``// are same then we can``        ``// increment the length``        ``if` `(arr[i] == arr[i + 1]) {``            ``j = j + 1;``        ``}``        ``else` `{` `            ``// Reinitialize j``            ``j = 1;``        ``}` `        ``// Compare the maximum``        ``// length e with j``        ``if` `(e < j) {``            ``e = j;``        ``}``    ``}` `    ``// Return max length``    ``return` `e;``}` `// Driver Code``int` `main()``{``    ``// Given array arr[]``    ``int` `arr[] = { 1, 2, 3, 4 };` `    ``int` `N = ``sizeof``(arr) / ``sizeof``(arr);` `    ``// Function Call``    ``cout << longest_subarray(arr, N);``}`

## Java

 `// Java program for the above approach``import` `java.util.*;` `class` `GFG{` `// Function to find the longest``// subarray with same element``static` `int` `longest_subarray(``int` `arr[], ``int` `d)``{``    ``int` `i = ``0``, j = ``1``, e = ``0``;` `    ``for``(i = ``0``; i < d - ``1``; i++)``    ``{``        ` `       ``// Check if the elements``       ``// are same then we can``       ``// increment the length``       ``if` `(arr[i] == arr[i + ``1``])``       ``{``           ``j = j + ``1``;``       ``}``       ``else``       ``{``           ` `           ``// Reinitialize j``           ``j = ``1``;``       ``}``       ` `       ``// Compare the maximum``       ``// length e with j``       ``if` `(e < j)``       ``{``           ``e = j;``       ``}``    ``}` `    ``// Return max length``    ``return` `e;``}` `// Driver Code``public` `static` `void` `main(String[] args)``{``    ` `    ``// Given array arr[]``    ``int` `arr[] = { ``1``, ``2``, ``3``, ``4` `};``    ``int` `N = arr.length;` `    ``// Function Call``    ``System.out.print(longest_subarray(arr, N));``}``}` `// This code is contributed by 29AjayKumar`

## Python3

 `# Python3 program for the above approach` `# Function to find the longest``# subarray with same element``def` `longest_subarray(arr, d):``    ` `    ``(i, j, e) ``=` `(``0``, ``1``, ``0``)``    ` `    ``for` `i ``in` `range``(d ``-` `1``):``        ` `        ``# Check if the elements``        ``# are same then we can``        ``# increment the length``        ``if` `arr[i] ``=``=` `arr[i ``+` `1``]:``            ``j ``+``=` `1``        ``else``:``            ` `            ``# Reinitialize j``            ``j ``=` `1``        ` `        ``# Compare the maximum``        ``# length e with j``        ``if` `e < j:``            ``e ``=` `j``    ` `    ``# Return max length``    ``return` `e` `# Driver code` `# Given list arr[]``arr ``=` `[ ``1``, ``2``, ``3``, ``4` `]``N ``=` `len``(arr)` `# Function call``print``(longest_subarray(arr, N))` `# This code is contributed by rutvik_56`

## C#

 `// C# program for the above approach``using` `System;` `class` `GFG{`` ` `// Function to find the longest``// subarray with same element``static` `int` `longest_subarray(``int` `[]arr, ``int` `d)``{``    ``int` `i = 0, j = 1, e = 0;`` ` `    ``for``(i = 0; i < d - 1; i++)``    ``{``         ` `       ``// Check if the elements``       ``// are same then we can``       ``// increment the length``       ``if` `(arr[i] == arr[i + 1])``       ``{``           ``j = j + 1;``       ``}``       ``else``       ``{``            ` `           ``// Reinitialize j``           ``j = 1;``       ``}``        ` `       ``// Compare the maximum``       ``// length e with j``       ``if` `(e < j)``       ``{``           ``e = j;``       ``}``    ``}`` ` `    ``// Return max length``    ``return` `e;``}`` ` `// Driver Code``public` `static` `void` `Main(String[] args)``{``     ` `    ``// Given array []arr``    ``int` `[]arr = { 1, 2, 3, 4 };``    ``int` `N = arr.Length;`` ` `    ``// Function Call``    ``Console.Write(longest_subarray(arr, N));``}``}` `// This code is contributed by 29AjayKumar`

## Javascript

 ``
Output:
`1`

Time Complexity: O(N)
Auxiliary Space: O(1)

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with experts, please refer DSA Live Classes for Working Professionals and Competitive Programming Live for Students.

My Personal Notes arrow_drop_up