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Move-to-front algorithm: Difference between revisions

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Move-to-front algorithm (view source)

Revision as of 22:09, 30 January 2022

7,192 bytes added ,  2 years ago
m
→‎{{header|Phix}}: added syntax colouring, marked p2js compatible
(Added solution for Action!)
m (→‎{{header|Phix}}: added syntax colouring, marked p2js compatible)
Line 1,955:
 
=={{header|Phix}}==
Equivalent longhand versions of the symtab reordering left in as comments
<lang Phix>function encode(string s)
<!--<lang Phix>(phixonline)-->
string symtab = "abcdefghijklmnopqrstuvwxyz"
<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</span>
sequence res = {}
<span style="color: #008080;">function</span> <span style="color: #000000;">encode</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">)</span>
for i=1 to length(s) do
<span style="color: #004080;">string</span> <span style="color: #000000;">symtab</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"abcdefghijklmnopqrstuvwxyz"</span>
integer ch = s[i]
<span style="color: #004080;">sequence</span> <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{}</span>
integer k = find(ch,symtab)
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">s</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
res &= k-1
<span style="color: #004080;">integer</span> <span style="color: #000000;">ch</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span> <span style="color: #000000;">k</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">ch</span><span style="color: #0000FF;">,</span><span style="color: #000000;">symtab</span><span style="color: #0000FF;">)</span>
for j=k to 2 by -1 do
<span style="color: #000000;">res</span> <span style="color: #0000FF;">&=</span> <span style="color: #000000;">k</span><span style="color: #0000FF;">-</span><span style="color: #000000;">1</span>
symtab[j] = symtab[j-1]▼
<span style="color: #000080;font-style:italic;">-- for j=k to 2 by -1 do
end for
-- symtab[1j] = chsymtab[j-1]
-- end for
-- symtab[1] = ch</span>▼
return res
<span style="color: #000000;">symtab</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..</span><span style="color: #000000;">k</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">ch</span><span style="color: #0000FF;">&</span><span style="color: #000000;">symtab</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..</span><span style="color: #000000;">k</span><span style="color: #0000FF;">-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span>
end function
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
 
<span style="color: #008080;">return</span> <span style="color: #000000;">res</span>
function decode(sequence s)
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
string symtab = "abcdefghijklmnopqrstuvwxyz"
string res = ""
<span style="color: #008080;">function</span> <span style="color: #000000;">decode</span><span style="color: #0000FF;">(</span><span style="color: #004080;">sequence</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">)</span>
for i=1 to length(s) do
<span style="color: #004080;">string</span> <span style="color: #000000;">symtab</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"abcdefghijklmnopqrstuvwxyz"</span>
integer k = s[i]+1
<span style="color: #004080;">string</span> <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">""</span>
integer ch = symtab[k]
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">s</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
res &= ch
<span style="color: #004080;">integer</span> <span style="color: #000000;">k</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]+</span><span style="color: #000000;">1</span>
for j=k to 2 by -1 do
<span style="color: #004080;">integer</span> <span style="color: #000000;">ch</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">symtab</span><span style="color: #0000FF;">[</span><span style="color: #000000;">k</span><span style="color: #0000FF;">]</span>
symtab[j] = symtab[j-1]
<span style="color: #000000;">res</span> <span style="color: #0000FF;">&=</span> <span style="color: #000000;">ch</span>
end for
<span style="color: #000080;font-style:italic;">-- for j=k to 2 by -1 do
▲ symtab[1] = ch
▲ -- symtab[j] = symtab[j-1]
end for
-- return res end for
▲ -- symtab[j1] = symtab[j-1]ch</span>
end function
<span style="color: #000000;">symtab</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..</span><span style="color: #000000;">k</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">ch</span><span style="color: #0000FF;">&</span><span style="color: #000000;">symtab</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..</span><span style="color: #000000;">k</span><span style="color: #0000FF;">-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span>
 
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
procedure test(string s)
<span style="color: #008080;">return</span> <span style="color: #000000;">res</span>
sequence e = encode(s)
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
string d = decode(e)
?{s,e,d,{"**ERROR**","ok"}[(s=d)+1]}
<span style="color: #008080;">procedure</span> <span style="color: #000000;">test</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">)</span>
end procedure
<span style="color: #004080;">sequence</span> <span style="color: #000000;">e</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">encode</span><span style="color: #0000FF;">(</span><span style="color: #000000;">s</span><span style="color: #0000FF;">)</span>
test("broood")
<span style="color: #004080;">string</span> <span style="color: #000000;">d</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">decode</span><span style="color: #0000FF;">(</span><span style="color: #000000;">e</span><span style="color: #0000FF;">)</span>
test("bananaaa")
<span style="color: #0000FF;">?{</span><span style="color: #000000;">s</span><span style="color: #0000FF;">,</span><span style="color: #000000;">e</span><span style="color: #0000FF;">,</span><span style="color: #000000;">d</span><span style="color: #0000FF;">,{</span><span style="color: #008000;">"**ERROR**"</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"ok"</span><span style="color: #0000FF;">}[(</span><span style="color: #000000;">s</span><span style="color: #0000FF;">=</span><span style="color: #000000;">d</span><span style="color: #0000FF;">)+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]}</span>
test("hiphophiphop")</lang>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #000000;">test</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"broood"</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">test</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"bananaaa"</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">test</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"hiphophiphop"</span><span style="color: #0000FF;">)</span>
<!--</lang>-->
{{out}}
<pre>
Petelomax
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