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 = 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
<?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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