Ninja And Matrix

Easy

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Average time to solve is 15m

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Problem statement

Ninja loves patterns and visuals and recently he learned about 2-dimensional matrices now he wants to use his pattern skills on it. He has been provided with a 2-dimensional matrix with a size of ‘N’x’N’ and he wants to print the matrix in a snake pattern. Formally speaking he wants to print every odd indexed row in reverse order(0-indexed) and even indexed row as it is on a single line.

EXAMPLE:

Input: 'N' = 2, ‘MAT’ = [[1, 2], [5, 6]]

Output: 1 2 6 5

 So the first row will be printed as it is and the second row will be printed in reverse order.

Detailed explanation ( Input/output format, Notes, Images )

Input Format :

The first line will contain the integer 'T', denoting the number of test cases.

For each test case, the first line will contain a single integer 'N', the size of the matrix ‘Mat’, and then the next ‘N’ lines will contain ‘N’ integers representing the matrix elements.

Output format :

For each test case, print the matrix in a specified manner on a new line.

Note :

You don't need to print anything. It has already been taken care of. Just implement the given function.

Constraints :

1 <= 'T' <= 10
1 <= 'N' <= 10^3
1 <= ‘MAT[i]’ <= 10^9

Time Limit: 1 sec

Sample Input 1 :

Sample Output 1 :

1 2 3 6 5 4 7 8 9 
5 10 15 20

Explanation Of Sample Input 1 :

For the first case:
The first row will be printed as it is and the second row will be printed in reverse order.

For the second case:
Similarly as for test 1.

Sample Input 2 :

Sample Output 2 :

1
4 4 6 6

Hint 1

Can you think of something like an even and odd row?

Approaches (1)

Approach 1

Naive

For each row, if the row is oddly indexed(0-indexed) then print it in reverse order or you can reverse the row, and then you can print it.

Algorithm :

Initialize a vector named ‘ANS’.
For each row from 0 <= row <= ‘N’-1:-
- If row %2 = 1 :-
  - Reverse the current row.
- Push every element of the current row into vector ‘ANS’.
Return vector ‘ANS’.

Time Complexity

Time Complexity :

O(N*N), Where ‘N’ is the number of rows and columns.

As we are traversing the whole matrix of size ‘N’*’N’.

Space Complexity

Space Complexity:

O(1).

As we are using no extra space.

(100% EXP penalty)

Ninja And Matrix

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