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 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.
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 manner void 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 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 = 3C = 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
<?php // PHP program to print matrix // in alternate manner $R = 3; $C = 3; // Function for print matrix // in alternate manner function convert($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 ?> |
Output:
1 2 3 1 2 3 4 5 6
Time Complexity : O(R*C)
Space Complexity : O(1)
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