Upside-down numbers: Difference between revisions
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Line 135:
5,000,000th : 82,485,246,852,682
50,000,000th : 9,285,587,463,255,281
</pre>
=={{header|jq}}==
'''Adapted from [[#Wren|Wren]]'''
{{works with|jq}}
'''Works with gojq, the Go implementation of jq, and with fq'''
The following solution relies on the built-in integer arithmetic capabilities of the selected implementation of jq. In the case of the C implementation, this precludes in principle the completion of the stretch task. In any case, the program below becomes very slow after the 50,000th upside-down number is generated, whichever of the above-mentioned implementations of jq is used.
<syntaxhighlight lang=jq>
# Output an unbounded stream of upside-down numbers
def genUpsideDown:
def wrappings: [
[1, 9], [2, 8], [3, 7], [4, 6], [5, 5],
[6, 4], [7, 3], [8, 2], [9, 1] ];
{ evens: [19, 28, 37, 46, 55, 64, 73, 82, 91],
odds: [5],
oddIndex: 0, evenIndex: 0, ndigits: 1, pow: 100 }
| while (true;
.emit = null
| if .ndigits % 2 == 1
then if (.odds|length) > .oddIndex
then .emit = .odds[.oddIndex]
| .oddIndex += 1
else # build next odds, but switch to evens
.nextOdds = []
| reduce wrappings[] as $w (.;
reduce .odds[] as $i (.;
.nextOdds += [$w[0] * .pow + $i * 10 + $w[1]] ) )
| .odds = .nextOdds
| .ndigits += 1
| .pow *= 10
| .oddIndex = 0
end
elif (.evens|length) > .evenIndex
then .emit = .evens[.evenIndex]
| .evenIndex += 1
else # build next evens, but switch to odds
.nextEvens = []
| reduce wrappings[] as $w (.;
reduce .evens[] as $i (.;
.nextEvens += [$w[0] * .pow + $i * 10 + $w[1]] ) )
| .evens = .nextEvens
| .ndigits += 1
| .pow *= 10
| .evenIndex = 0
end )
| select(.emit).emit ;
def task($limit):
{ count:0, ud50s: [], pow: 50 }
| foreach limit($limit; genUpsideDown) as $n (.;
.emit = null
| .count += 1
| if .count < 50
then .ud50s += [$n]
elif .count == 50
then .emit = {"First 50 upside down numbers:": (.ud50s + [$n]) }
| .pow = 500
elif .count == .pow
then .emit = {pow, $n}
| .pow *= 10
else .
end)
| select(.emit).emit;
task(5000000)
</syntaxhighlight>
{{ouput}}
The jq and gojq programs were terminated after the results shown below were obtained.
<pre>
{"First 50 upside down numbers:":[5,19,28,37,46,55,64,73,82,91,159,258,357,456,555,654,753,852,951,1199,1289,1379,1469,1559,1649,1739,1829,1919,2198,2288,2378,2468,2558,2648,2738,2828,2918,3197,3287,3377,3467,3557,3647,3737,3827,3917,4196,4286,4376,4466]}
{"pow":500,"n":494616}
{"pow":5000,"n":56546545}
{"pow":50000,"n":6441469664}
</pre>
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