problem details

problem

6

title

ZigZag Conversion

short 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)

Problem Statement

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

My solution

Runtime: 148 ms Memory Usage: 12.6 MB

class Solution:
    def convert(self, s: 'str', numRows: 'int') -> 'str':
        if numRows == 0:
            return ''
        if numRows == 1:
            return s

        l = ['' for i in range(numRows)]
        incr = 1
        counter = 0
        for i in range(len(s)):
            l[counter] += s[i]
            if (incr > 0 and (counter+1)%numRows == 0) or (incr < 0 and counter == 0):
                incr = -1 * incr
            counter += incr
        return "".join(l)

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