Zigzag String

The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)

P.......A........H.......N
..A..P....L....S....I...I....G
....Y.........I........R

And then read line by line: PAHNAPLSIIGYIR
Write the code that will take a string and make this conversion given a number of rows:

string convert(string text, int nRows);
convert("PAYPALISHIRING", 3) should return "PAHNAPLSIIGYIR"

**Example 2 : **
ABCD, 2 can be written as

A....C
...B....D

and hence the answer would be ACBD.

NOTE: You only need to implement the given function. Do not read input, instead use the arguments to the function. Do not print the output, instead return values as specified. Still have a question? Checkout Sample Codes for more details.