Reading a Zigzag by Rows

Medium

The text text is written as a snake across rows lines: the first letter goes on the top line, the next ones go down one line at a time to the bottom line, then diagonally back up to the top, down again, and so on. For example, SNOWFALL on three lines looks like this:


S   F
N W A L
O   L

Then the lines are read from top to bottom, each from left to right, and joined together. Return the resulting string. With rows = 1 the text does not change.

Example 1

text="SNOWFALL", rows=3 → 'SFNWALOL'

The three-row snake is S . . . F . . . / . N . W . A . L / . . O . . . L .. Reading row by row gives SF + NWAL + OL.

Example 2

text="abcdef", rows=2 → 'acebdf'

With two rows the letters simply alternate: even positions on top, odd ones below.

Example 3

text="hi", rows=5 → 'hi'

There are more rows than letters, so the text stays a single column and comes out unchanged.

Constraints

1 ≤ len(text) ≤ 1000
text consists of English letters (lowercase and uppercase), , and .
1 ≤ rows ≤ 1000

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Topics

String

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Input

text="SNOWFALL", rows=3

Expected

'SFNWALOL'

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