Created
September 1, 2016 18:19
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Esse programa foi feito para transformar expressões da notação infixa para a pós-fixada (polonesa inversa) e vice-versa.
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"use strict"; | |
/* | |
Esse programa foi feito para transformar expressões da notação infixa para a pós-fixada (polonesa inversa) e vice-versa. | |
*/ | |
function infixToPosfix (infixExpression) { | |
const postfixExpression = [] | |
const operators = [] | |
for (const char of infixExpression) { | |
if (['(', ' '].includes(char)) { | |
continue | |
} | |
else if (char == ')') { | |
if (operators.length < 1) { | |
throw new Error('A expressão é mal-formada.') | |
} | |
postfixExpression.push(operators.pop()) | |
} | |
else if (['+', '-', '*', '/'].includes(char)) { | |
operators.push(char) | |
} | |
else { | |
postfixExpression.push(char) | |
} | |
} | |
return postfixExpression.join('') | |
} | |
function postfixToInfix (postfixExpression) { | |
const operands = [] | |
for (const char of postfixExpression) { | |
if (['(', ')', ' '].includes(char)) { | |
continue | |
} | |
else if (['+', '-', '*', '/'].includes(char)) { | |
if (operands.length < 2) { | |
throw new Error('A expressão é mal-formada.') | |
} | |
const rightOperand = operands.pop() | |
const leftOperand = operands.pop() | |
operands.push(`(${leftOperand} ${char} ${rightOperand})`) | |
} | |
else { | |
operands.push(char) | |
} | |
} | |
return operands.pop() | |
} | |
const infixExpressions = [ | |
'(((((a+b)+c)+(d /e))-(f*g))-h)', | |
'(((a+b)+((c+d)/e))-(f*(g-h)))' | |
] | |
const postfixExpressions = [ | |
'abc+-de*/fgh--*', | |
'abc*/' | |
] | |
infixExpressions.forEach(expression => console.log(infixToPosfix(expression))) | |
postfixExpressions.forEach(expression => console.log(postfixToInfix(expression))) |
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