Maximum length of subarray such that all elements are equal in the subarray
Last Updated :
18 May, 2023
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: 5
Explanation:
The subarray {5, 5, 5, 5, 5} has maximum length 5 with identical elements.
Input: arr[] = {1, 2, 3, 4}
Output: 1
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:
- Traverse the array and check if the current element is equal to the next element then increase the value of the current length variable.
- Now, compare the current length with max length to update the maximum length of the subarray.
- 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 <iostream>
using namespace std;
// Function to find the longest
// subarray with same element
int longest_subarray(int arr[], int d)
{
if(d <= 1) return 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[0]);
// Function Call
cout << longest_subarray(arr, N);
}
// 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)
{
if (d <= 1)
return 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 program for the above approach
# Function to find the longest
# subarray with same element
def longest_subarray(arr, d):
if d <= 1:
return 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# 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)
{
if (d <= 1)
return 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
<script>
// javascript program for the above approach
// Function to find the longest
// subarray with same element
function longest_subarray(arr , d)
{
if(d <= 1) return d;
var 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
// Given array arr
var arr = [ 1, 2, 3, 4 ];
var N = arr.length;
// Function Call
document.write(longest_subarray(arr, N));
// This code is contributed by todaysgaurav
</script>
Time Complexity: O(N)
Auxiliary Space: O(1)
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