24 lines
750 B
Text
24 lines
750 B
Text
# Input: an array representing a stack, with .[-1] being its top.
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# Output: the updated array after applying `op`
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def rpn(op):
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def two: .[-2:];
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def update($x): (.[:-2] + [$x]);
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if length<=1 then .
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elif op == "+" then update(two | add)
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elif op == "*" then update(two | (.[0] * .[1]))
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elif op == "/" then update(two | (.[0] / .[1]))
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elif op == "-" then update(two | (.[0] - .[1]))
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elif op == "^" then update(two | (pow(.[0]; .[1])))
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else ("ignoring unrecognized op \(op)" | debug) as $debug | .
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end;
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def eval:
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foreach .[] as $item ([];
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if ($item | type) == "number" then . + [$item]
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else rpn($item)
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end;
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"\($item) => \(.)" ) ;
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"3 4 2 * 1 5 - 2 3 ^ ^ / +"
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| split(" ") | map( (try tonumber) // .)
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| eval
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