# Find the Longest subarray such that difference between adjacent elements is K

• Last Updated : 31 Mar, 2022

Given an array arr[] of size N, and integer K. The task is to find the longest subarray with the difference between adjacent elements as K.

Examples:

Input: arr[] = { 5, 5, 5, 10, 8, 6, 12, 13 }, K =1
Output: {12, 13}
Explanation: This is the longest subarray with difference between adjacents as 1.

Input: arr[] = {4, 6, 8, 9, 8, 12, 14, 17, 15}, K = 2
Output: {4, 6, 8}

Approach: Starting from the first element of the array, find the first valid sub-array and store its length and starting point. Then starting from the next element (the first element that wasn’t included in the first sub-array), find another valid sub-array and keep on updating the maximum length and start point. Repeat the process until all the valid sub-arrays have been found then print the maximum length sub-array.

Below is the implementation of the above approach.

## C++

 `// C++ implementation of the approach``#include ``using` `namespace` `std;` `// Function to return the maximum length``// sub-array such that the``// absolute difference between every two``// consecutive elements is K``void` `getMaxLengthSubarray(``int` `arr[],``                          ``int` `N, ``int` `K)``{``    ``int` `l = N;``    ``int` `i = 0, maxlen = 0;``    ``int` `max_len_start, max_len_end;``    ``while` `(i < l) {``        ``int` `j = i;``        ``while` `(i + 1 < l``               ``&& (``abs``(arr[i]``                       ``- arr[i + 1]) == K)) {``            ``i++;``        ``}` `        ``// Length of the valid sub-array``        ``// currently under consideration``        ``int` `currLen = i - j + 1;` `        ``// Update the maximum length subarray``        ``if` `(maxlen < currLen) {``            ``maxlen = currLen;``            ``max_len_start = j;``            ``max_len_end = i;``        ``}` `        ``if` `(j == i)``            ``i++;``    ``}` `    ``// Print the maximum length subarray``    ``for` `(``int` `p = max_len_start;``         ``p <= max_len_end; p++)``        ``cout << arr[p] << ``" "``;``}` `// Driver code``int` `main()``{``    ``int` `arr[] = { 4, 6, 8, 9, 8, 12,``                 ``14, 17, 15 };``    ``int` `K = 2;``    ``int` `N = ``sizeof``(arr) / ``sizeof``(arr);``    ``getMaxLengthSubarray(arr, N, K);``    ``return` `0;``}`

## Java

 `// Java program for the above approach``import` `java.util.*;``public` `class` `GFG``{` `// Function to return the maximum length``// sub-array such that the``// absolute difference between every two``// consecutive elements is K``static` `void` `getMaxLengthSubarray(``int` `arr[],``                          ``int` `N, ``int` `K)``{``    ``int` `l = N;``    ``int` `i = ``0``, maxlen = ``0``;``    ``int` `max_len_start = ``0``, max_len_end = ``0``;``    ``while` `(i < l) {``        ``int` `j = i;``        ``while` `(i + ``1` `< l``               ``&& (Math.abs(arr[i]``                       ``- arr[i + ``1``]) == K)) {``            ``i++;``        ``}` `        ``// Length of the valid sub-array``        ``// currently under consideration``        ``int` `currLen = i - j + ``1``;` `        ``// Update the maximum length subarray``        ``if` `(maxlen < currLen) {``            ``maxlen = currLen;``            ``max_len_start = j;``            ``max_len_end = i;``        ``}` `        ``if` `(j == i)``            ``i++;``    ``}` `    ``// Print the maximum length subarray``    ``for` `(``int` `p = max_len_start;``         ``p <= max_len_end; p++)``        ``System.out.print(arr[p] + ``" "``);``}` `// Driver code``public` `static` `void` `main(String args[])``{``    ``int` `arr[] = { ``4``, ``6``, ``8``, ``9``, ``8``, ``12``,``                 ``14``, ``17``, ``15` `};``    ``int` `K = ``2``;``    ``int` `N =  arr.length; ``    ``getMaxLengthSubarray(arr, N, K);``}``}` `// This code is contributed by Samim Hossain Mondal.`

## Python3

 `# Python program to implement``# the above approach` `# Function to return the maximum length``# sub-array such that the``# absolute difference between every two``# consecutive elements is K``def` `getMaxLengthSubarray(arr, N, K) :``    ` `    ``l ``=` `N``    ``i ``=` `0``    ``maxlen ``=` `0``    ``while` `(i < l) :``        ``j ``=` `i``        ``while` `(i ``+` `1` `< l``               ``and` `(``abs``(arr[i]``                       ``-` `arr[i ``+` `1``]) ``=``=` `K)) :``            ``i ``+``=` `1``        ` `        ``# Length of the valid sub-array``        ``# currently under consideration``        ``currLen ``=` `i ``-` `j ``+` `1` `        ``# Update the maximum length subarray``        ``if` `(maxlen < currLen) :``            ``maxlen ``=` `currLen``            ``max_len_start ``=` `j``            ``max_len_end ``=` `i``        ` `        ``if` `(j ``=``=` `i) :``            ``i ``+``=` `1``    ` `    ``# Print the maximum length subarray``    ``for` `p ``in` `range``(max_len_start, max_len_end``+``1``, ``1``) :``        ``print``(arr[p], end``=``" "``)` `# Driver code``arr ``=` `[ ``4``, ``6``, ``8``, ``9``, ``8``, ``12``,``                 ``14``, ``17``, ``15` `]``K ``=` `2``N ``=` `len``(arr)``getMaxLengthSubarray(arr, N, K)` `# This code is contributed by avijitmondal1998`

## C#

 `// C# program for the above approach``using` `System;``class` `GFG``{` `// Function to return the maximum length``// sub-array such that the``// absolute difference between every two``// consecutive elements is K``static` `void` `getMaxLengthSubarray(``int` `[]arr,``                          ``int` `N, ``int` `K)``{``    ``int` `l = N;``    ``int` `i = 0, maxlen = 0;``    ``int` `max_len_start = 0, max_len_end = 0;``    ``while` `(i < l) {``        ``int` `j = i;``        ``while` `(i + 1 < l``               ``&& (Math.Abs(arr[i]``                       ``- arr[i + 1]) == K)) {``            ``i++;``        ``}` `        ``// Length of the valid sub-array``        ``// currently under consideration``        ``int` `currLen = i - j + 1;` `        ``// Update the maximum length subarray``        ``if` `(maxlen < currLen) {``            ``maxlen = currLen;``            ``max_len_start = j;``            ``max_len_end = i;``        ``}` `        ``if` `(j == i)``            ``i++;``    ``}` `    ``// Print the maximum length subarray``    ``for` `(``int` `p = max_len_start;``         ``p <= max_len_end; p++)``        ``Console.Write(arr[p] + ``" "``);``}` `// Driver code``public` `static` `void` `Main()``{``    ``int` `[]arr = { 4, 6, 8, 9, 8, 12,``                 ``14, 17, 15 };``    ``int` `K = 2;``    ``int` `N =  arr.Length; ``    ``getMaxLengthSubarray(arr, N, K);``}``}` `// This code is contributed by Samim Hossain Mondal.`

## Javascript

 ``

Output
`4 6 8 `

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

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