0006. ZigZag Conversion

https://leetcode.com/problems/zigzag-conversion

Description

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 s, int numRows);

Example 1:

**Input:** s = "PAYPALISHIRING", numRows = 3
**Output:** "PAHNAPLSIIGYIR"

Example 2:

**Input:** s = "PAYPALISHIRING", numRows = 4
**Output:** "PINALSIGYAHRPI"
**Explanation:**
P     I    N
A   L S  I G
Y A   H R
P     I

Example 3:

**Input:** s = "A", numRows = 1
**Output:** "A"

Constraints:

• 1 <= s.length <= 1000

• s consists of English letters (lower-case and upper-case), ',' and '.'.

• 1 <= numRows <= 1000

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