30 lines
982 B
Markdown
30 lines
982 B
Markdown
const postFix = RPN => {
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let convert = RPN.replace(/\^/g,'**').split(/\s+/g).filter(el => !/\s+/.test(el) && el !== '')
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let stack = []
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let result = []
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let friends = {"+" : ["+","-","*","/"],"-":[],"/":["*"],"*":["/","*"],"**":["+","-","*","/"]}
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convert.forEach(symbol => {
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if(!isNaN(parseFloat(symbol)) && isFinite(symbol)){
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result.push(symbol)
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}
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else if (Object.keys(friends).includes(symbol)) {
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a = result.pop()
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b = result.pop()
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if(stack.length !==0){
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if(friends[symbol].includes(stack.pop())){
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result.push(`${b} ${symbol} ${a}`)
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stack.push(symbol)
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}
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else{
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result.push(`(${b}) ${symbol} ${a}`)
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stack.push(symbol)
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}
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}
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else {result.push(`${b} ${symbol} ${a}`);stack.push(symbol)}
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}
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else throw `${symbol} is not a recognized symbol`
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})
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if(result.length === 1) return result.pop()
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else throw `${RPN} is not a correct RPN`
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}
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