# Sort first half in ascending and second half in descending order | Set 2

Given an array of integers, sort the first half of the array in ascending order and second half in descending order.
Examples:

```Input : arr[] = {10, 20, 30, 40}
Output : arr[] = {10, 20, 40, 30}

Input : arr[] = {5, 4, 6, 2, 1, 3, 8, 9, 7 }
Output : arr[] = {2, 4, 5, 6, 9, 8, 7, 3, 1 }
```

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

We have discussed a solution that only prints the required order in Sort first half in ascending and second half in descending order | Set 1

Simple Approach
The idea is simple, we sort the first half in increasing order and second half in decreasing using library function. Most of the languages like Java, C++ provide provision to sort a subarray in a specified order. In this post, a different solution is discussed that modifies the original array.

## C++

 `// C++ program to sort first half in increasing ` `// order and second half in decreasing ` `#include ` `using` `namespace` `std; ` ` `  `void` `mySort(``int` `arr[], ``int` `n) ` `{ ` `    ``sort(arr, arr+n/2); ` `    ``sort(arr+n/2, arr+n, greater<``int``>()); ` `} ` ` `  `int` `main() ` `{ ` `    ``int` `arr[] = { 5, 4, 6, 2, 1, 3, 8, 9, 7 }; ` `    ``int` `n = ``sizeof``(arr)/``sizeof``(arr); ` `    ``mySort(arr, n); ` `    ``cout << ``"Modified Array : \n"``; ` `    ``for` `(``int` `i=0; i

## Java

 `// Java program to sort first half in increasing ` `// order and second half in decreasing ` `import` `java.util.*; ` ` `  `public` `class` `SortExample { ` `    ``static` `void` `mySort(Integer[] arr) ` `    ``{ ` `        ``int` `n = arr.length; ` ` `  `        ``// Sort subarray from index 1 to 4, i.e., ` `        ``// only sort subarray {7, 6, 45, 21} and ` `        ``// keep other elements as it is. ` `        ``Arrays.sort(arr, ``0``, n / ``2``); ` `        ``Arrays.sort(arr, n / ``2``, n, Collections.reverseOrder()); ` `    ``} ` ` `  `    ``public` `static` `void` `main(String[] args) ` `    ``{ ` `        ``// Our arr contains 8 elements ` `        ``Integer[] arr = { ``5``, ``4``, ``6``, ``2``, ``1``, ``3``, ``8``, ``9``, ``7` `}; ` `        ``mySort(arr); ` `        ``System.out.printf(``"Modified arr[] : %s"``, ` `                          ``Arrays.toString(arr)); ` `    ``} ` `} `

## Python 3

 `# Python3 program to sort first half in increasing ` `# order and second half in decreasing ` ` `  `# required sorting function ` `def` `mySort( arr, n): ` `     `  `    ``arr1 ``=` `arr[:n``/``/``2``] ` `    ``arr2 ``=` `arr[n``/``/``2``:] ` `    ``arr1.sort() ` `    ``arr2.sort(reverse``=``True``) ` `    ``return` `arr1``+``arr2 ` `     `  `     `  ` `  `# driving function ` `if` `__name__``=``=``'__main__'``: ` `    ``arr``=` `[``5``, ``4``, ``6``, ``2``, ``1``, ``3``, ``8``, ``9``, ``7` `] ` `    ``n ``=` `len``(arr) ` `    ``arr``=``mySort(arr, n) ` `    ``print``( ``"Modified Array : "``) ` `    ``print``(arr) ` ` `  `# this code is contributed by ash264 `

## C#

 `// C# program to sort first half in increasing ` `// order and second half in decreasing ` `using` `System; ` ` `  `public` `class` `SortExample  ` `{ ` `    ``static` `void` `mySort(``int``[] arr) ` `    ``{ ` `        ``int` `n = arr.Length; ` ` `  `        ``// Sort subarray from index 1 to 4, i.e., ` `        ``// only sort subarray {7, 6, 45, 21} and ` `        ``// keep other elements as it is. ` `        ``Array.Sort(arr, 0, n / 2); ` `        ``Array.Sort(arr, n / 2, (n/2)+1); ` `        ``Array.Reverse(arr, n / 2, (n/2)+1); ` `    ``} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `Main(String[] args) ` `    ``{ ` `        ``// Our arr contains 8 elements ` `        ``int``[] arr = { 5, 4, 6, 2, 1, 3, 8, 9, 7 }; ` `        ``mySort(arr); ` `        ``Console.Write(``"Modified arr[] : {0}"``, ` `                        ``String.Join(``" "``,arr)); ` `    ``} ` `} ` ` `  `/* This code contributed by PrinciRaj1992 */`

## PHP

 ` `

Output:

```Modified array :
2 4 5 6 9 8 7 3 1
```

Alternate Solution
1) Sort the whole array in ascending order.
2) Reverse the second half after sorting.

## C++

 `// C++ program to sort first half in increasing ` `// order and second half in decreasing ` `#include ` `using` `namespace` `std; ` ` `  `void` `mySort(``int` `arr[], ``int` `n) ` `{ ` `    ``// Sort the first half ` `    ``sort(arr, arr+n/2); ` `    ``sort(arr+n/2, arr+n); ` ` `  `    ``reverse(arr+n/2, arr+n); ` `} ` ` `  `int` `main() ` `{ ` `    ``int` `arr[] = { 5, 4, 6, 2, 1, 3, 8, 9, 7 }; ` `    ``int` `n = ``sizeof``(arr)/``sizeof``(arr); ` `    ``mySort(arr, n); ` `    ``cout << ``"Modified Array : \n"``; ` `    ``for` `(``int` `i=0; i

## Java

 `// Java program to sort first half in increasing ` `// order and second half in decreasing ` `import` `java.util.*; ` ` `  `public` `class` `SortExample { ` `    ``static` `void` `mySort(Integer[] arr) ` `    ``{ ` `        ``int` `n = arr.length; ` `         `  `        ``// Sort the whole array  ` `        ``Arrays.sort(arr, ``0``, n/``2``); ` `        ``Arrays.sort(arr, n/``2``, n); ` ` `  `        ``// Reverse the second half ` `        ``int` `low = n/``2``, high = n-``1``; ` `        ``while` `(low < high) ` `        ``{ ` `            ``Integer temp = arr[low]; ` `            ``arr[low] = arr[high]; ` `            ``arr[high] = temp; ` `            ``low++; high--; ` `        ``}   ` `    ``} ` ` `  `    ``public` `static` `void` `main(String[] args) ` `    ``{ ` `        ``// Our arr contains 8 elements ` `        ``Integer[] arr = { ``5``, ``4``, ``6``, ``2``, ``1``, ``3``, ``8``, ``9``, ``7` `}; ` `        ``mySort(arr); ` `        ``System.out.printf(``"Modified arr[] : %s"``, ` `                          ``Arrays.toString(arr)); ` `    ``} ` `} `

## Python3

 `# Python3 program to sort first half in increasing ` `# order and second half in decreasing ` `def` `mySort(arr): ` `    ``n ``=` `len``(arr); ` ` `  `    ``# Sort the whole array ` `    ``arr1 ``=` `arr[:n ``/``/` `2``] ` `    ``arr2 ``=` `arr[n ``/``/` `2``:] ` `    ``arr1.sort() ` `    ``arr2.sort() ` `    ``arr ``=` `arr1 ``+` `arr2 ` ` `  `    ``# Reverse the second half ` `    ``low ``=` `n ``/``/` `2``; ` `    ``high ``=` `n ``-` `1``; ` `    ``while` `(low < high): ` `        ``temp ``=` `arr[low]; ` `        ``arr[low] ``=` `arr[high]; ` `        ``arr[high] ``=` `temp; ` `        ``low ``+``=` `1``; ` `        ``high ``-``=` `1``; ` `    ``return` `arr; ` ` `  `# Driver code ` `if` `__name__ ``=``=` `'__main__'``: ` `     `  `    ``# Our arr contains 8 elements ` `    ``arr ``=` `[``5``, ``4``, ``6``, ``2``, ``1``, ``3``, ``8``, ``9``, ``7``]; ` `    ``arr ``=` `mySort(arr); ` `    ``print``(``"Modified Array : "``) ` `    ``print``(arr) ` ` `  `# This code is contributed by 29AjayKumar `

## C#

 `// C# program to sort first half in increasing  ` `// order and second half in decreasing  ` `using` `System; ` ` `  `public` `class` `SortExample  ` `{  ` `    ``static` `void` `mySort(``int``[] arr)  ` `    ``{  ` `        ``int` `n = arr.Length;  ` `         `  `        ``// Sort the whole array  ` `        ``Array.Sort(arr, 0, n/2);  ` `        ``Array.Sort(arr, n/2, n/2+1);  ` ` `  `        ``// Reverse the second half  ` `        ``int` `low = n/2, high = n-1;  ` `        ``while` `(low < high)  ` `        ``{  ` `            ``int` `temp = arr[low];  ` `            ``arr[low] = arr[high];  ` `            ``arr[high] = temp;  ` `            ``low++; high--;  ` `        ``}  ` `    ``}  ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `Main(String[] args)  ` `    ``{  ` `        ``// Our arr contains 8 elements  ` `        ``int``[] arr = { 5, 4, 6, 2, 1, 3, 8, 9, 7 };  ` `        ``mySort(arr);  ` `        ``Console.WriteLine(``"Modified arr[] : {0}"``,  ` `                        ``String.Join(``", "``,arr));  ` `    ``}  ` `}  ` ` `  `// This code has been contributed by 29AjayKumar `

Output:

```Modified arr[] : [2, 4, 5, 6, 9, 8, 7, 3, 1]
```

Time Complexity of both approaches is O(n Log n)

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