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June 30, 2021 13:22
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An O(log_n) palindrome check algorithm, the number of letter iterations is halved (rounded up when the half is a rational number).
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#!/bin/bash/python | |
# | |
# Requires Python 3 and above | |
# | |
# Example | |
# | |
# R A D A R | |
# 1 2 3 4 5 | |
# | |
# H A N N A H | |
# 1 2 3 4 5 6 | |
# | |
# The opposite of 2 is 4... so on, so forth. | |
def check_palindrome(the_word): | |
word_length = len(the_word) | |
# No need to go all the way through... | |
for i in range(int(word_length / 2)): | |
# If you have 5 fingers, the third one is the middle | |
# If the no. of your finger is 6, consider the gap as 3.5 | |
middle_index = (word_length + 1) / 2.00 | |
# Most arrays start at 0, but... | |
# Letter index must start by 1 | |
li = i + 1 | |
# The opposite version of your 2nd finger is your 4th finger | |
c = int((middle_index * 2) - li) | |
#If the opposites don't match... | |
if the_word[i] != the_word[c - 1]: | |
return False | |
return True | |
print("Enter a word (case sensitive): ") | |
THE_WORD = input() | |
print (check_palindrome(THE_WORD)) |
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I didn't know how to use the ceiling function back then.