Stern-Brocot sequence: Difference between revisions

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=={{header|Phix}}==
<!--<lang Phix>sequence sb = {1,1}(phixonline)-->
<span style="color: #004080;">sequence</span> <span style="color: #000000;">sb</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #000000;">1</span><span style="color: #0000FF;">}</span>
integer c = 2
<span style="color: #004080;">integer</span> <span style="color: #000000;">c</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">2</span>
 
function stern_brocot(integer n)
<span style="color: #008080;">function</span> <span style="color: #000000;">stern_brocot</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">)</span>
while length(sb)<n do
<span style="color: #008080;">while</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">sb</span><span style="color: #0000FF;">)<</span><span style="color: #000000;">n</span> <span style="color: #008080;">do</span>
sb &= sb[c]+sb[c-1] & sb[c]
<span style="color: #000000;">sb</span> <span style="color: #0000FF;">&=</span> <span style="color: #000000;">sb</span><span style="color: #0000FF;">[</span><span style="color: #000000;">c</span><span style="color: #0000FF;">]+</span><span style="color: #000000;">sb</span><span style="color: #0000FF;">[</span><span style="color: #000000;">c</span><span style="color: #0000FF;">-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">&</span> <span style="color: #000000;">sb</span><span style="color: #0000FF;">[</span><span style="color: #000000;">c</span><span style="color: #0000FF;">]</span>
c += 1
<span style="color: #000000;">c</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">1</span>
end while
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
return sb[1..n]
<span style="color: #008080;">return</span> <span style="color: #000000;">sb</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..</span><span style="color: #000000;">n</span><span style="color: #0000FF;">]</span>
end function
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
 
sequence s = stern_brocot(15)
<span style="color: #004080;">sequence</span> <span style="color: #000000;">s</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">stern_brocot</span><span style="color: #0000FF;">(</span><span style="color: #000000;">15</span><span style="color: #0000FF;">)</span>
puts(1,"first 15:")
<span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"first 15:"</span><span style="color: #0000FF;">)</span>
?s
<span style="color: #0000FF;">?</span><span style="color: #000000;">s</span>
integer n = 16, k
<span style="color: #004080;">integer</span> <span style="color: #000000;">n</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">16</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">k</span>
sequence idx = tagset(10)
<span style="color: #004080;">sequence</span> <span style="color: #000000;">idx</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">tagset</span><span style="color: #0000FF;">(</span><span style="color: #000000;">10</span><span style="color: #0000FF;">)</span>
for i=1 to length(idx) do
<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;">idx</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
while 1 do
<span style="color: #008080;">while</span> <span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
k = find(idx[i],s)
<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;">idx</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span><span style="color: #000000;">s</span><span style="color: #0000FF;">)</span>
if k!=0 then exit end if
<span style="color: #008080;">if</span> <span style="color: #000000;">k</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">0</span> <span style="color: #008080;">then</span> <span style="color: #008080;">exit</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
n *= 2
<span style="color: #000000;">n</span> <span style="color: #0000FF;">*=</span> <span style="color: #000000;">2</span>
s = stern_brocot(n)
<span style="color: #000000;">s</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">stern_brocot</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">)</span>
end while
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
idx[i] = k
<span style="color: #000000;">idx</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">k</span>
end for
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
puts(1,"indexes of 1..10:")
<span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"indexes of 1..10:"</span><span style="color: #0000FF;">)</span>
?idx
<span style="color: #0000FF;">?</span><span style="color: #000000;">idx</span>
puts(1,"index of 100:")
<span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"index of 100:"</span><span style="color: #0000FF;">)</span>
while 1 do
<span style="color: #008080;">while</span> <span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
k = find(100,s)
<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;">100</span><span style="color: #0000FF;">,</span><span style="color: #000000;">s</span><span style="color: #0000FF;">)</span>
if k!=0 then exit end if
<span style="color: #008080;">if</span> <span style="color: #000000;">k</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">0</span> <span style="color: #008080;">then</span> <span style="color: #008080;">exit</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
n *= 2
<span style="color: #000000;">n</span> <span style="color: #0000FF;">*=</span> <span style="color: #000000;">2</span>
s = stern_brocot(n)
<span style="color: #000000;">s</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">stern_brocot</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">)</span>
end while
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
?k
<span style="color: #0000FF;">?</span><span style="color: #000000;">k</span>
s = stern_brocot(1000)
<span style="color: #000000;">s</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">stern_brocot</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1000</span><span style="color: #0000FF;">)</span>
integer maxgcd = 1
<span style="color: #004080;">integer</span> <span style="color: #000000;">maxgcd</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">1</span>
for i=1 to 999 do
<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: #000000;">999</span> <span style="color: #008080;">do</span>
maxgcd = max(gcd(s[i],s[i+1]),maxgcd)
<span style="color: #000000;">maxgcd</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">max</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">gcd</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;">s</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]),</span><span style="color: #000000;">maxgcd</span><span style="color: #0000FF;">)</span>
end for
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
printf(1,"max gcd:%d\n",{maxgcd})</lang>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"max gcd:%d\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">maxgcd</span><span style="color: #0000FF;">})</span>
<!--</lang>-->
{{Out}}
<pre>
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