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da6d8e39c9
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Test, Build, and Deploy / test-build-deploy (push) Failing after 27s
next_row prepends 1, walks adjacent pairs (x, y) emitting x+y,
appends a final 1:
let rec next_row prev =
let rec aux a =
match a with
| [_] -> [1]
| x :: y :: rest -> (x + y) :: aux (y :: rest)
| [] -> []
in
1 :: aux prev
row n iterates next_row n times starting from [1] using a ref +
'for _ = 1 to n do r := next_row !r done'.
row 10 = [1;10;45;120;210;252;210;120;45;10;1]
List.nth (row 10) 5 = 252 = C(10, 5)
Exercises three-arm match including [_] singleton wildcard, x :: y
:: rest binding, and the for-loop with wildcard counter. 45 baseline
programs total.
20 lines
276 B
OCaml
20 lines
276 B
OCaml
let rec next_row prev =
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let rec aux a =
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match a with
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| [_] -> [1]
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| x :: y :: rest -> (x + y) :: aux (y :: rest)
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| [] -> []
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in
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1 :: aux prev
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let row n =
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let r = ref [1] in
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for _ = 1 to n do
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r := next_row !r
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done;
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!r
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;;
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List.nth (row 10) 5
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