18 lines
419 B
Plaintext
18 lines
419 B
Plaintext
left(a, n) := makelist(a[i], i, 1, n)$
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right(a, n) := block([m: length(a)], makelist(a[i], i, m - n + 1, m))$
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a: [ ]$
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for year from 1900 thru 2100 do
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for month in [1, 3, 5, 7, 8, 10, 12] do
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if weekday(year, month, 1) = 'friday then
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a: endcons([year, month], a)$
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length(a);
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201
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left(a, 5);
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[[1901,3],[1902,8],[1903,5],[1904,1],[1904,7]]
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right(a, 5);
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[[2097,3],[2098,8],[2099,5],[2100,1],[2100,10]]
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