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
Solutions
1. String
# Time: O(n^2)
# Space: O(n)
class Solution:
def convert(self, s: str, numRows: int) -> str:
if numRows == 1:
return s
n = len(s)
interval = 2 * (numRows - 1)
res = ''
# first row
for i in range(0, n, interval):
res += s[i]
# middle lines
for r in range(1, numRows - 1):
inter = 2 * r
i = r
while i < n:
res += s[i]
inter = interval - inter
i += inter
for i in range(numRows-1, n, interval):
res += s[i]
return res
# 1158/1158 cases passed (52 ms)
# Your runtime beats 86.83 % of python3 submissions
# Your memory usage beats 100 % of python3 submissions (12.9 MB)