Created
June 10, 2015 11:52
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solveRPN :: String -> Double | |
-- solveRPN expression = head (foldl foldingFunction [] (words expression)) | |
solveRPN = head . foldl foldingFunction [] . words | |
-- where foldingFunction stack item = ... | |
where foldingFunction (x:y:ys) "*" = (y * x):ys | |
foldingFunction (x:y:ys) "+" = (y + x):ys | |
foldingFunction (x:y:ys) "-" = (y - x):ys | |
foldingFunction (x:y:ys) "/" = (y / x):ys | |
foldingFunction xs numberString = read numberString:xs | |
main = do | |
print $ solveRPN "3 2 +" | |
print $ solveRPN "3 3.5 +" | |
print $ solveRPN "10 4 3 + 2 * -" | |
print $ solveRPN "90 34 12 33 55 66 + * - +" |
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