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

Source: leetcode | Difficulty: MEDIUM_HARD
Tags: String algorithms

Starter code: class Solution:
    def convert(self, s: str, numRows: int) -> str:
        

Solutions:
class Solution(object):

	def convert(self, s, numRows):
		if numRows == 1:
			return s
		zigzag = ['' for i in range(numRows)]
		row = 0
		step = 1
		for c in s:
			if row == 0:
				step = 1
			if row == numRows - 1:
				step = -1
			zigzag[row] += c
			row += step
		return ''.join(zigzag)


class Solution:

	def convert(self, s, numRows):
		if numRows == 1 or numRows >= len(s):
			return s
		result = [''] * numRows
		(index, step) = (0, 1)
		for c in s:
			result[index] += c
			if index == 0:
				step = 1
			elif index == numRows - 1:
				step = -1
			index += step
		return ''.join(result)


class Solution:

	def convert(self, s, numRows):
		if numRows == 1 or numRows >= len(s):
			return s
		list_string = [''] * numRows
		(index, step) = (0, 1)
		for i in s:
			list_string[index] += i
			if index == 0:
				step = 1
			elif index == numRows - 1:
				step = -1
			index += step
		return ''.join(list_string)


class Solution:

	def convert(self, s, nRows):
		if nRows == 1:
			return s
		tmp = ['' for i in range(nRows)]
		index = -1
		step = 1
		for i in range(len(s)):
			index += step
			if index == nRows:
				index -= 2
				step = -1
			elif index == -1:
				index = 1
				step = 1
			tmp[index] += s[i]
		return ''.join(tmp)


class Solution:

	def convert(self, s, numRows):
		if numRows == 1:
			return s
		count = len(s)
		if count <= 1:
			return s
		result = []
		deltSmall = numRows - 1
		deltBig = 2 * deltSmall
		for i in range(0, numRows):
			k = i
			if i == 0 or i == deltSmall:
				while k < count:
					result.append(s[k])
					k += deltBig
			else:
				while k < count:
					top = k - k % deltSmall
					bottom = top + deltSmall
					result.append(s[k])
					nextk = 2 * bottom - k
					if nextk < count:
						result.append(s[nextk])
					k += deltBig
		return ''.join(result)


class Solution:

	def convert(self, s, numRows):
		if len(s) == 0 or numRows < 1:
			return ''
		if numRows == 1:
			return s
		maxStep = (numRows - 1) * 2
		reStr = ''
		for i in range(numRows):
			j = i
			step = maxStep - 2 * i
			while j < len(s):
				reStr += s[j]
				if step == 0:
					j += maxStep
				else:
					j += step
				step = maxStep - step
				if step == 0:
					step = maxStep
		return reStr