# Check if an array is increasing or decreasing

Given an array arr[] of N elements where N ≥ 2, the task is to check the type of array whether it is:

1. Increasing.
2. Decreasing.
3. Increasing then decreasing.
4. Decreasing then increasing.

Note that the given array is definitely one of the given types.

Examples:

Input: arr[] = {1, 2, 3, 4, 5}
Output: Increasing

Input: arr[] = {1, 2, 4, 3}
Output: Increasing then decreasing

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: The following conditions must satitisfy for:

1. Increasing array: The first two and the last two elements must be in increasing order.
2. Decreasing array: The first two and the last two elements must be in decreasing order.
3. Increasing then decreasing array: The first two elements must be in increasing order and the last two elements must be in decreasing order.
4. Decreasing then increasing array: The first two elements must be in decreasing order and the last two elements must be in increasing order.

Below is the implementation of the above approach:

## C++

 `// C++ implementation of the approach ` `#include ` `using` `namespace` `std; ` ` `  `// Function to check the type of the array ` `void` `checkType(``int` `arr[], ``int` `n) ` `{ ` ` `  `    ``// If the first two and the last two elements ` `    ``// of the array are in increasing order ` `    ``if` `(arr[0] <= arr[1] && arr[n - 2] <= arr[n - 1]) ` `        ``cout << ``"Increasing"``; ` ` `  `    ``// If the first two and the last two elements ` `    ``// of the array are in decreasing order ` `    ``else` `if` `(arr[0] >= arr[1] && arr[n - 2] >= arr[n - 1]) ` `        ``cout << ``"Decreasing"``; ` ` `  `    ``// If the first two elements of the array are in ` `    ``// increasing order and the last two elements ` `    ``// of the array are in decreasing order ` `    ``else` `if` `(arr[0] <= arr[1] && arr[n - 2] >= arr[n - 1]) ` `        ``cout << ``"Increasing then decreasing"``; ` ` `  `    ``// If the first two elements of the array are in ` `    ``// decreasing order and the last two elements ` `    ``// of the array are in increasing order ` `    ``else` `        ``cout << ``"Decreasing then increasing"``; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``int` `arr[] = { 1, 2, 3, 4 }; ` `    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr[0]); ` ` `  `    ``checkType(arr, n); ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java implementation of the approach  ` `import` `java.math.*; ` ` `  `class` `GFG ` `{ ` ` `  `    ``// Function to check the type of the array  ` `    ``public` `static` `void` `checkType(``int` `arr[], ``int` `n)  ` `    ``{  ` `     `  `        ``// If the first two and the last two elements  ` `        ``// of the array are in increasing order  ` `        ``if` `(arr[``0``] <= arr[``1``] &&  ` `            ``arr[n - ``2``] <= arr[n - ``1``])  ` `            ``System.out.println(``"Increasing"``);  ` `     `  `        ``// If the first two and the last two elements  ` `        ``// of the array are in decreasing order  ` `        ``else` `if` `(arr[``0``] >= arr[``1``] &&  ` `                 ``arr[n - ``2``] >= arr[n - ``1``])  ` `            ``System.out.println(``"Decreasing"``);  ` `     `  `        ``// If the first two elements of the array are in  ` `        ``// increasing order and the last two elements  ` `        ``// of the array are in decreasing order  ` `        ``else` `if` `(arr[``0``] <= arr[``1``] && ` `                 ``arr[n - ``2``] >= arr[n - ``1``])  ` `            ``System.out.println(``"Increasing then decreasing"``);  ` ` `  `        ``// If the first two elements of the array are in  ` `        ``// decreasing order and the last two elements  ` `        ``// of the array are in increasing order  ` `        ``else` `            ``System.out.println(``"Decreasing then increasing"``); ` `    ``} ` `         `  ` `  `    ``// Driver code  ` `    ``public` `static` `void` `main(String[] args)  ` `    ``{  ` `        ``int``[] arr = ``new` `int``[]{ ``1``, ``2``, ``3``, ``4` `}; ` `         `  `        ``int` `n = arr.length; ` ` `  `        ``checkType(arr, n);  ` `    ``} ` `} ` ` `  `// This code is contributed by Naman_Garg `

## Python3

 `# Python3 implementation of the approach  ` ` `  `# Function to check the type of the array  ` `def` `checkType(arr, n):  ` ` `  `    ``# If the first two and the last two elements  ` `    ``# of the array are in increasing order  ` `    ``if` `(arr[``0``] <``=` `arr[``1``] ``and`  `        ``arr[n ``-` `2``] <``=` `arr[n ``-` `1``]) : ` `        ``print``(``"Increasing"``);  ` ` `  `    ``# If the first two and the last two elements  ` `    ``# of the array are in decreasing order  ` `    ``elif` `(arr[``0``] >``=` `arr[``1``] ``and`  `          ``arr[n ``-` `2``] >``=` `arr[n ``-` `1``]) : ` `        ``print``(``"Decreasing"``);  ` ` `  `    ``# If the first two elements of the array are in  ` `    ``# increasing order and the last two elements  ` `    ``# of the array are in decreasing order  ` `    ``elif` `(arr[``0``] <``=` `arr[``1``] ``and`  `          ``arr[n ``-` `2``] >``=` `arr[n ``-` `1``]) :  ` `        ``print``(``"Increasing then decreasing"``);  ` ` `  `    ``# If the first two elements of the array are in  ` `    ``# decreasing order and the last two elements  ` `    ``# of the array are in increasing order  ` `    ``else` `: ` `        ``print``(``"Decreasing then increasing"``);  ` ` `  `# Driver code  ` `if` `__name__ ``=``=` `"__main__"` `:  ` ` `  `    ``arr ``=` `[ ``1``, ``2``, ``3``, ``4` `];  ` `    ``n ``=` `len``(arr);  ` ` `  `    ``checkType(arr, n);  ` ` `  `# This code is contributed by AnkitRai01 `

## C#

 `// C# implementation of the approach  ` `using` `System; ` `class` `GFG ` `{ ` `     `  `    ``// Function to check the type of the array  ` `    ``public` `static` `void` `checkType(``int` `[]arr, ``int` `n)  ` `    ``{  ` `     `  `        ``// If the first two and the last two elements  ` `        ``// of the array are in increasing order  ` `        ``if` `(arr[0] <= arr[1] &&  ` `            ``arr[n - 2] <= arr[n - 1])  ` `            ``Console.Write(``"Increasing"``);  ` `     `  `        ``// If the first two and the last two elements  ` `        ``// of the array are in decreasing order  ` `        ``else` `if` `(arr[0] >= arr[1] &&  ` `                 ``arr[n - 2] >= arr[n - 1])  ` `            ``Console.Write(``"Decreasing"``);  ` `     `  `        ``// If the first two elements of the array are in  ` `        ``// increasing order and the last two elements  ` `        ``// of the array are in decreasing order  ` `        ``else` `if` `(arr[0] <= arr[1] && ` `                 ``arr[n - 2] >= arr[n - 1])  ` `            ``Console.Write(``"Increasing then decreasing"``);  ` ` `  `        ``// If the first two elements of the array are in  ` `        ``// decreasing order and the last two elements  ` `        ``// of the array are in increasing order  ` `        ``else` `            ``Console.Write(``"Decreasing then increasing"``); ` `    ``} ` ` `  `    ``// Driver code  ` `    ``static` `public` `void` `Main () ` `    ``{ ` `        ``int``[] arr = ``new` `int``[]{ 1, 2, 3, 4 }; ` `         `  `        ``int` `n = arr.Length; ` ` `  `        ``checkType(arr, n);  ` `    ``} ` `} ` ` `  `// This code is contributed by ajit `

Output:

```Increasing
```

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Improved By : AnkitRai01, Naman_Garg, jit_t

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