Brendan Chen
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38 lines
1.1 KiB
Python
38 lines
1.1 KiB
Python
# Make a calculator using Reverse Polish Notation. Use recursion.
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# The Reverse Polish syntax completely removes the need for parentheses.
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#
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# Syntax examples:
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# "3 + 2" -> ["3", "2", "+"]
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# "3 * 4 + 2" -> ["3", "4", "*", "2", "+"]
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# "3 * (4 + 2)" -> ["3", "4", "2", "+", "*"]
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#
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# Example for how to evaluate ["3", "4", "2", "+", "*"]:
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# Start with "4 2 +" -> "6"
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# Then "3 6 *" -> "18"
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# Start with the "innermost" expression and work backwards (this is the recursion part)
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#
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# For help, email me@bchen.dev
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# Use this function definition:
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def rpn(expression: list[str]) -> int:
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return 0
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# The following test cases should pass (please copy this into your code):
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tests = [
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(["3", "2", "+"], 5),
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(["3", "4", "*"], 12),
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(["3", "4", "2", "+", "*"], 18),
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([], 0),
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(["50", "2", "/"], 25),
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(["5", "2", "/"], 2), # for division, cast to int using int(num)
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(["5", "4", "3", "-", "*"], 5),
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]
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for case in tests:
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result = rpn(case[0])
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expected = case[1]
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if result == expected:
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print(f"PASS: expected {expected}, got {result} for {case[0]}")
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else:
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print(f"FAIL: expected {expected}, got {result} for {case[0]}")
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