Longest common suffix
- Task
The goal is to write a function to find the longest common suffix string amongst an array of strings.
Julia
<lang julia>function longestcommonsuffix(strings)
n, nmax = 0, minimum(length, strings) nmax == 0 && return "" while n <= nmax && all(s -> s[end-n] == strings[end][end-n], strings) n += 1 end return strings[1][end-n+1:end]
end
println(longestcommonsuffix(["baabababc","baabc","bbbabc"])) println(longestcommonsuffix(["baabababc","baabc","bbbazc"]))
println(longestcommonsuffix([""]))</lang>
- Output:
abc c
Raku
<lang perl6>sub longest-common-suffix ( *@words ) {
return unless +@words; my $min = @words».chars.min; for 1 .. * { return @words[0].substr(* - $min) if $_ > $min; next if @words».substr(* - $_).Set == 1; return @words[0].substr(* - $_ + 1); }
}
say "{$_.raku} - LCS: >{longest-common-suffix $_}<" for
<Sunday Monday Tuesday Wednesday Thursday Friday Saturday>, <Sondag Maandag Dinsdag Woensdag Donderdag Vrydag Saterdag dag>, ( 2347, 9312347, 'acx5g2347', 12.02347 ), <longest common suffix>, ('one, Hey!', 'three, Hey!', 'ale, Hey!', 'me, Hey!'), </lang>
- Output:
("Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday") - LCS: >day< ("Sondag", "Maandag", "Dinsdag", "Woensdag", "Donderdag", "Vrydag", "Saterdag", "dag") - LCS: >dag< (2347, 9312347, "acx5g2347", 12.02347) - LCS: >2347< ("longest", "common", "suffix") - LCS: >< ("one, Hey!", "three, Hey!", "ale, Hey!", "me, Hey!") - LCS: >e, Hey!< "" - LCS: ><
REXX
Essentially, this REXX version simply reversed the strings, and then finds the longest common prefix. <lang rexx>/*REXX program finds the longest common suffix contained in an array of strings. */ parse arg z; z= space(z) /*obtain optional arguments from the CL*/ if z==|z=="," then z='baabababc baabc bbbabc' /*Not specified? Then use the default.*/ z= space(z); #= words(z) /*#: the number of words in the list. */ say 'There are ' # " words in the list: " z zr= reverse(z) /*reverse Z, find longest common prefix*/ @= word(zr, 1); m= length(@) /*get 1st word in reversed string; len.*/
do j=2 to #; x= word(zr, j) /*obtain a word (string) from the list.*/ t= compare(@, x) /*compare to the "base" word/string. */ if t==1 then do; @=; leave /*A mismatch of strings? Then leave, */ end /*no sense in comparing anymore strings*/ if t==0 & @==x then t= length(@) + 1 /*Both strings equal? Compute length. */ if t>=m then iterate /*T ≥ M? Then it's not longest string.*/ m= t - 1; @= left(@, max(0, m) ) /*redefine max length & the base string*/ end /*j*/
say /*stick a fork in it, we're all done. */ if m==0 then say 'There is no common suffix.'
else say 'The longest common suffix is: ' right( word(z, 1), m)</lang>
- output when using the default input:
There are 3 words in the list: baabababc baabc bbbabc The longest common suffix is: abc
Ring
<lang ring> load "stdlib.ring"
pre = ["baabababc","baabc","bbbabc"] len = len(pre) lenList = list(len) sub = list(len)
see "Input:" + nl see pre
for n = 1 to len
temp = pre[n] pre[n] = rever(temp)
next
for n = 1 to len
lenList[n] = len(pre[n])
next
lenList = sort(lenList) lenMax = lenList[1]
for m = 1 to lenMax
check = 0 sub1 = substr(pre[1],1,m) sub2 = substr(pre[2],1,m) sub3 = substr(pre[3],1,m) if sub1 = sub2 and sub2 = sub3 check = 1 ok if check = 1 longest = m ok
next
longPrefix = substr(pre[1],1,longest) longPrefix = rever(longPrefix)
see "Longest common suffix = " + longPrefix + nl
func rever(cstr)
cStr2 = "" for x = len(cStr) to 1 step -1 cStr2 = cStr2 + cStr[x] next return cStr2
</lang>
- Output:
Input: baabababc baabc bbbabc Longest common suffix = abc