15 lines
761 B
Plaintext
15 lines
761 B
Plaintext
cal_j:(_jd[19000101]+!(-/_jd 21010101 19000101)) / enumerate the calendar
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is_we:(cal_j!7) _lin 4 5 6 / identify friday saturdays and sundays
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m:__dj[cal_j]%100 / label the months
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mi:&15=+/'is_we[=m] / group by month and sum the weekend days
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`0:,"There are ",($#mi)," months with five weekends"
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m5:(?m)[mi]
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`0:$5#m5
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`0:,"..."
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`0:$-5#m5
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y:1900+!201 / enumerate the years in the range
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y5:?_ m5%100 / label the years of the months
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yn5:y@&~y _lin y5 / find any years not in the 5 weekend month list
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`0:,"There are ",($#yn5)," years without any five-weekend months"
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`0:,1_,/",",/:$yn5
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