# Print a matrix in alternate manner (left to right then right to left)

Given a 2D array, the task is to print the 2D in alternate manner (First row from left to right, then from right to left, and so on).

Examples:

```Input : arr[][2] = {{1, 2}
{2, 3}};
Output : 1  2  3  2

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

The solution of this problem is that run two loops and print row in left to right and right to left manners. We maintain a flag to see if current row should be printed from left to right or right to left. We toggle the flag after every iteration.

Implementation:

## C++

 `// C++ program to print matrix in alternate manner` `#include` `using` `namespace` `std;` `#define R 3` `#define C 3`   `// Function for print matrix in alternate manner` `void` `convert(``int` `arr[R][C])` `{` `    ``bool` `leftToRight = ``true``;` `    ``for` `(``int` `i=0; i=0; j--)` `                ``printf``(``"%d "``,arr[i][j]);` `        ``}`   `        ``leftToRight = !leftToRight;` `    ``}` `}`   `// Driver code` `int` `main()` `{` `    ``int` `arr[][C] =` `    ``{` `        ``{ 1 , 2 , 3 },` `        ``{ 3 , 2 , 1 },` `        ``{ 4 , 5 , 6 },` `    ``};`   `    ``convert(arr);` `    ``return` `0;` `}`

## Java

 `//Java program to print matrix in alternate manner ` `class` `GFG {`   `    ``static` `final` `int` `R = ``3``;` `    ``static` `final` `int` `C = ``3``;`   `// Function for print matrix in alternate manner ` `    ``static` `void` `convert(``int` `arr[][]) {` `        ``boolean` `leftToRight = ``true``;` `        ``for` `(``int` `i = ``0``; i < R; i++) {` `            ``if` `(leftToRight) {` `                ``for` `(``int` `j = ``0``; j < C; j++) {` `                    ``System.out.printf(``"%d "``, arr[i][j]);` `                ``}` `            ``} ``else` `{` `                ``for` `(``int` `j = C - ``1``; j >= ``0``; j--) {` `                    ``System.out.printf(``"%d "``, arr[i][j]);` `                ``}` `            ``}`   `            ``leftToRight = !leftToRight;` `        ``}` `    ``}`   `// Driver code ` `    ``static` `public` `void` `main(String[] args) {` `        ``int` `arr[][]` `                ``= {` `                    ``{``1``, ``2``, ``3``},` `                    ``{``3``, ``2``, ``1``},` `                    ``{``4``, ``5``, ``6``},};`   `        ``convert(arr);` `    ``}` `}`   `// This code is contributed by Rajput-Ji`

## Python 3

 `# Python 3 program to print matrix ` `# in alternate manner` `R ``=` `3` `C ``=` `3`   `# Function for print matrix` `# in alternate manner` `def` `convert(arr):`   `    ``leftToRight ``=` `True` `    ``for` `i ``in` `range``(R):` `        ``if` `(leftToRight):` `            ``for` `j ``in` `range``(C):` `                ``print``(arr[i][j], end ``=` `" "``)` `    `  `        ``else``:` `            ``for` `j ``in` `range``(C ``-` `1``, ``-``1``, ``-``1``):` `                ``print``(arr[i][j], end ``=` `" "``)`   `        ``leftToRight ``=` `not` `leftToRight`   `# Driver code` `if` `__name__ ``=``=` `"__main__"``:` `    ``arr ``=``[[ ``1` `, ``2` `, ``3` `],` `          ``[ ``3` `, ``2` `, ``1` `],` `          ``[ ``4` `, ``5` `, ``6` `]]`   `    ``convert(arr)`   `# This code is contributed ` `# by ChitraNayal`

## C#

 `    `  `//C# program to print matrix in alternate manner` `using` `System;` `public` `class` `GFG {` ` `  `    ``static` `readonly` `int` `R = 3;` `    ``static` `readonly` `int` `C = 3;` ` `  `// Function for print matrix in alternate manner ` `    ``static` `void` `convert(``int` `[,]arr) {` `        ``bool` `leftToRight = ``true``;` `        ``for` `(``int` `i = 0; i < R; i++) {` `            ``if` `(leftToRight) {` `                ``for` `(``int` `j = 0; j < C; j++) {` `                    ``Console.Write(arr[i,j]+``" "``);` `                ``}` `            ``} ``else` `{` `                ``for` `(``int` `j = C - 1; j >= 0; j--) {` `                    ``Console.Write(arr[i,j]+``" "``);` `                ``}` `            ``}` ` `  `            ``leftToRight = !leftToRight;` `        ``}` `    ``}` ` `  `// Driver code ` `    ``static` `public` `void` `Main() {` `        ``int` `[,]arr` `                ``= {` `                    ``{1, 2, 3},` `                    ``{3, 2, 1},` `                    ``{4, 5, 6},};` ` `  `        ``convert(arr);` `    ``}` `}` ` `  `// This code is contributed by Rajput-Ji`

## PHP

 `= 0; ``\$j``--)` `                ``echo` `\$arr``[``\$i``][``\$j``], ``" "``;` `        ``}`   `        ``\$leftToRight` `= !``\$leftToRight``;` `    ``}` `}`   `// Driver code` `\$arr` `= ``array``(``array``(1 , 2 , 3 ),` `             ``array``(3 , 2 , 1 ),` `             ``array``(4 , 5 , 6 ));`   `convert(``\$arr``);`   `// This code is contributed by ajit` `?>`

## Javascript

 ``

Output

`1 2 3 1 2 3 4 5 6 `

Time Complexity : O(R*C)
Space Complexity : O(1)

If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Feeling lost in the world of random DSA topics, wasting time without progress? It's time for a change! Join our DSA course, where we'll guide you on an exciting journey to master DSA efficiently and on schedule.
Ready to dive in? Explore our Free Demo Content and join our DSA course, trusted by over 100,000 geeks!