Given a string and number of rows ‘n’. Print the string formed by concatenating n rows when the input string is written in row-wise Zig-Zag fashion.
Example 1:
Input:
str = "ABCDEFGH"
n = 2
Output: "ACEGBDFH"
Explanation:
Let us write input string in
Zig-Zag fashion in 2 rows.
A C E G
B D F H
Now concatenate the two rows and ignore
spaces in every row. We get "ACEGBDFH"
Example 2:
Input:
str = "GEEKSFORGEEKS"
n = 3
Output: GSGSEKFREKEOE
Explanation:
Let us write input string in
Zig-Zag fashion in 3 rows.
G S G S
E K F R E K
E O E
Now concatenate the two rows and ignore spaces
in every row. We get "GSGSEKFREKEOE"
Your Task:
You need not read input or print anything. Your task is to complete the function convert() which takes 2 arguments(string str, integer n) and returns the resultant string.
Expected Time Complexity: O(|str|).
Expected Auxiliary Space: O(|str|).
Constraints:
1 ≤ N ≤ 10^{5}

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