# Java Program to Rotate matrix by 45 degrees

• Last Updated : 27 Jan, 2022

Given a matrix mat[][] of size N*N, the task is to rotate the matrix by 45 degrees and print the matrix.

Examples:

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

Input: N = 4,
mat[][] = {{2, 5, 7, 2},
{9, 1, 4, 3},
{5, 8, 2, 3},
{6, 4, 6, 3}}

Output:
2
9 5
5 1 7
6 8 4 2
4 2 3
6 3
3

Approach: Follow the steps given below in order to solve the problem:

1. Store the diagonal elements in a list using a counter variable.
2. Print the number of spaces required to make the output look like the desired pattern.
3. Print the list elements after reversing the list.
4. Traverse through only diagonal elements to optimize the time taken by the operation.

Below is the implementation of the above approach:

## Java

 `// Java program for ``// the above approach ``import` `java.util.*;``class` `GFG{`` ` `// Function to rotate ``// matrix by 45 degree``static` `void` `matrix(``int` `n, ``int` `m, ``                   ``int` `[][]li)``{``  ``// Counter Variable ``  ``int` `ctr = ``0``;`` ` `  ``while` `(ctr < ``2` `* n - ``1``)``  ``{``    ``for``(``int` `i = ``0``; i < Math.abs(n - ctr - ``1``);``            ``i++)``    ``{``      ``System.out.print(``" "``);``    ``}`` ` `    ``Vector lst = ``new` `Vector();`` ` `    ``// Iterate [0, m] ``    ``for``(``int` `i = ``0``; i < m; i++)``    ``{``      ``// Iterate [0, n] ``      ``for``(``int` `j = ``0``; j < n; j++)``      ``{``        ``// Diagonal Elements ``        ``// Condition ``        ``if` `(i + j == ctr)``        ``{``          ``// Appending the ``          ``// Diagonal Elements ``          ``lst.add(li[i][j]);``        ``}``      ``}``    ``}`` ` `    ``// Printing reversed Diagonal ``    ``// Elements ``    ``for``(``int` `i = lst.size() - ``1``; i >= ``0``; i--)``    ``{``      ``System.out.print(lst.get(i) + ``" "``);``    ``}``     ` `    ``System.out.println();``    ``ctr += ``1``;``  ``}``}`` ` `// Driver code    ``public` `static` `void` `main(String[] args)``{    ``  ``// Dimensions of Matrix ``  ``int` `n = ``8``;``  ``int` `m = n; `` ` `  ``// Given matrix ``  ``int``[][] li = {{``4``, ``5``, ``6``, ``9``, ``8``, ``7``, ``1``, ``4``}, ``                ``{``1``, ``5``, ``9``, ``7``, ``5``, ``3``, ``1``, ``6``}, ``                ``{``7``, ``5``, ``3``, ``1``, ``5``, ``9``, ``8``, ``0``}, ``                ``{``6``, ``5``, ``4``, ``7``, ``8``, ``9``, ``3``, ``7``}, ``                ``{``3``, ``5``, ``6``, ``4``, ``8``, ``9``, ``2``, ``1``}, ``                ``{``3``, ``1``, ``6``, ``4``, ``7``, ``9``, ``5``, ``0``}, ``                ``{``8``, ``0``, ``7``, ``2``, ``3``, ``1``, ``0``, ``8``}, ``                ``{``7``, ``5``, ``3``, ``1``, ``5``, ``9``, ``8``, ``5``}};`` ` `  ``// Function call ``  ``matrix(n, m, li);``}``}`` ` `// This code is contributed by Princi Singh`

Output:

```       4
1 5
7 5 6
6 5 9 9
3 5 3 7 8
3 5 4 1 5 7
8 1 6 7 5 3 1
7 0 6 4 8 9 1 4
5 7 4 8 9 8 6
3 2 7 9 3 0
1 3 9 2 7
5 1 5 1
9 0 0
8 8
5

```

Time Complexity: O(N2)
Auxiliary Space: O(1)

Please refer complete article on Rotate matrix by 45 degrees for more details!

My Personal Notes arrow_drop_up