Longest common prefix: Difference between revisions
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m (→version 2: added/changed whitespace and comments to the program and the output section.) |
m (→version 3: added/changed whitespace and comments in the REXX program and the output section header.) |
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===version 3=== |
===version 3=== |
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This REXX version explicitly shows ''null'' values and the number of strings specified. |
This REXX version explicitly shows ''null'' values and the number of strings specified. |
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<lang rexx>/*REXX |
<lang rexx>/*REXX program computes the longest common prefix of any number of strings. */ |
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say LCP('interspecies', "interstellar", 'interstate') |
say LCP('interspecies', "interstellar", 'interstate') |
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say LCP('throne', "throne") /* |
say LCP('throne', "throne") /*2 strings, they are exactly the same.*/ |
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say LCP('throne', "dungeon") /*2 completely different strings.*/ |
say LCP('throne', "dungeon") /*2 completely different strings. */ |
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say LCP('throne', '', "throne") /*3 strings, middle |
say LCP('throne', '', "throne") /*3 strings, the middle string is null.*/ |
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say LCP('cheese') /*just a single cheesy argument. */ |
say LCP('cheese') /*just a single cheesy argument. */ |
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say LCP('') /*just a single null argument. */ |
say LCP('') /*just a single null argument. */ |
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say LCP() /*no arguments specified at all. */ |
say LCP() /*no arguments are specified at all. */ |
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say LCP('prefix', "suffix") /*two mostly different strings. */ |
say LCP('prefix', "suffix") /*two mostly different strings. */ |
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say LCP('foo', "foobar") |
say LCP('foo', "foobar") /*two mostly similar strings. */ |
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say LCP('a', "b", 'c', "aaa") /*four strings, mostly different.*/ |
say LCP('a', "b", 'c', "aaa") /*four strings, mostly different. */ |
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exit /*stick a fork in it, we're done.*/ |
exit /*stick a fork in it, we're all done. */ |
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/*────────────────────────────────────────────────────────────────────────────*/ |
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/*──────────────────────────────────LCP subroutine──────────────────────*/ |
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LCP: @=arg(1); m=length(@); a=arg(); say copies('▒',60) |
LCP: @=arg(1); m=length(@); a=arg(); say copies('▒',60) |
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say '────────────── number of strings specified:' a |
say '────────────── number of strings specified:' a |
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do i=1 for a; say '────────────── string' i":" showNull(arg(i)); end |
do i=1 for a; say '────────────── string' i":" showNull(arg(i)); end |
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do j=2 to a; x=arg(j); t=compare(@,x) /*compare to next.*/ |
do j=2 to a; x=arg(j); t=compare(@,x) /*compare to next.*/ |
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if t==1 | x=='' then do; @=; leave; end /*mismatch of strs*/ |
if t==1 | x=='' then do; @=; leave; end /*mismatch of strs*/ |
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if t==0 & @==x then t=length(@)+1 /*both are equal. */ |
if t==0 & @==x then t=length(@) + 1 /*both are equal. */ |
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if t>=m then iterate /*not longest str.*/ |
if t>=m then iterate /*not longest str.*/ |
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m=t-1; @=left(@,max(0,m)) /*define maximum. */ |
m=t-1; @=left(@, max(0, m)) /*define maximum. */ |
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end /*j*/ |
end /*j*/ |
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return ' longest common prefix=' showNull(@) /*return answer. */ |
return ' longest common prefix=' showNull(@) /*return answer. */ |
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/*────────────────────────────────────────────────────────────────────────────*/ |
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/*──────────────────────────────────SHOWNULL subroutine─────────────────*/ |
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showNull: procedure; parse arg z; if z=='' then z='«null»'; return z</lang> |
showNull: procedure; parse arg z; if z=='' then z='«null»'; return z</lang> |
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'''output''' when using the default inputs: |
'''output''' when using the default inputs: |
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<pre> |
<pre> |
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