algorithm-in-python/string/manacher.py

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''' mbinary
#########################################################################
# File : manacher.py
# Author: mbinary
# Mail: zhuheqin1@gmail.com
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# Blog: https://mbinary.xyz
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# Github: https://github.com/mbinary
# Created Time: 2018-07-06 15:56
# Description:
#########################################################################
'''
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class Solution:
def longestPalindrome(self, s):
"""
:type s: str
:rtype: str
"""
n = len(s)
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s2 = '$#'+'#'.join(s)+'#@'
ct = [0]*(2*n+4)
mid = 1
for cur in range(1, 2*n+2):
if cur < mid+ct[mid]:
ct[cur] = min(ct[2*mid-cur], mid+ct[mid]-cur)
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else:
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ct[cur] = 1
while s2[cur-ct[cur]] == s2[cur+ct[cur]]:
ct[cur] += 1
if cur+ct[cur] > mid+ct[mid]:
mid = cur
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mx = max(ct)
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idxs = [i for i, j in enumerate(ct) if j == mx]
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p = idxs[0]
for i in idxs:
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if s2[i] == '#':
p = i
rst = s2[p-mx+1:p+mx].replace('#', '')
return rst