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Longest palindromic substrings: Difference between revisions
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The longest palindromic substring of abaracadabra is: "ara"
</pre>
=={{header|Nim}}==
Simple algorithm but working on Unicode code points.
<lang Nim>import sequtils, strutils, unicode
func isPalindrome(s: seq[Rune]): bool =
## Return true if a sequence of runes is a palindrome.
for i in 1..(s.len shr 1):
if s[i - 1] != s[^i]:
return false
result = true
func lps(s: string): seq[string] =
var maxLength = 0
var list: seq[seq[Rune]]
let r = s.toRunes
for first in 0..r.high:
for last in first..r.high:
let candidate = r[first..last]
if candidate.isPalindrome():
if candidate.len > maxLength:
list = @[candidate]
maxLength = candidate.len
elif candidate.len == maxLength:
list.add candidate
if maxLength > 1:
result = list.mapIt($it)
for str in ["babaccd", "rotator", "several", "palindrome", "piété", "tantôt", "étêté"]:
let result = lps(str)
if result.len == 0:
echo str, " → ", "<no palindromic substring of two of more letters found>"
else:
echo str, " → ", result.join(", ")</lang>
{{out}}
<pre>babaccd → bab, aba
rotator → rotator
several → eve
palindrome → <no palindromic substring of two of more letters found>
piété → été
tantôt → tôt
étêté → étêté</pre>
=={{header|Perl}}==
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