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zigzag-conversion.py
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zigzag-conversion.py
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"""
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
"""
# V0
# V1
# https://blog.csdn.net/coder_orz/article/details/52039689
# https://blog.csdn.net/fuxuemingzhu/article/details/80830509
class Solution(object):
def convert(self, s, numRows):
"""
:type s: str
:type numRows: int
:rtype: str
"""
if numRows <= 1 or numRows >= len(s):
return s
arr = [''] * numRows
line, step = 0, -1
for c in s:
arr[line] += c
if line % (numRows-1) == 0:
step = - step
line += step
return ''.join(arr)
# V2
class Solution(object):
def convert(self, s, numRows):
"""
:type s: str
:type numRows: int
:rtype: str
"""
if numRows == 1:
return s
step, zigzag = 2 * numRows - 2, ""
for i in range(numRows):
for j in range(i, len(s), step):
zigzag += s[j]
if 0 < i < numRows - 1 and j + step - 2 * i < len(s):
zigzag += s[j + step - 2 * i]
return zigzag