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<bits/stdc++.h>using namespace std;#define R 3#define C 3// Function for print matrix in alternate mannervoid convert(int arr[R][C]){ bool leftToRight = true; for (int i=0; i<R; i++) { if (leftToRight) { for (int j=0; j<C; j++) printf("%d ", arr[i][j]); } else { for (int j=C-1; j>=0; j--) printf("%d ",arr[i][j]); } leftToRight = !leftToRight; }}// Driver codeint 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 mannerR = 3C = 3# Function for print matrix# in alternate mannerdef 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 codeif __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 mannerusing 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
<?php// PHP program to print matrix // in alternate manner$R = 3;$C = 3;// Function for print matrix// in alternate mannerfunction convert($arr){ global $R; global $C; $leftToRight = true; for ($i = 0; $i < $R; $i++) { if ($leftToRight) { for ($j = 0; $j < $C; $j++) echo $arr[$i][$j], " "; } else { for ($j = $C - 1; $j >= 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
<script>// Javascript program to print matrix in alternate manner let R = 3; let C = 3; // Function for print matrix in alternate manner function convert(arr) { let leftToRight = true; for (let i = 0; i < R; i++) { if (leftToRight) { for (let j = 0; j < C; j++) { document.write(arr[i][j]+" "); } } else { for (let j = C - 1; j >= 0; j--) { document.write( arr[i][j]+" "); } } leftToRight = !leftToRight; } } // Driver code let arr =[[ 1 , 2 , 3 ], [ 3 , 2 , 1 ], [ 4 , 5 , 6 ]] convert(arr) // This code is contributed by avanitrachhadiya2155</script> |
Output
1 2 3 1 2 3 4 5 6
Time Complexity : O(R*C)
Space Complexity : O(1)
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