47 lines
1 KiB
Go
47 lines
1 KiB
Go
package mathevaluator
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import (
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"math"
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"strconv"
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"strings"
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"github.com/fotonmoton/algorithms/fundamentals/stack"
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)
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// Dijkstra's two stack algorithm for equation evaluation
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func Evaluate(exression string) int {
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operations := stack.NewStack[string]()
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values := stack.NewStack[int]()
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for _, part := range strings.Split(exression, " ") {
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isOperation := part == "+" || part == "-" || part == "*" || part == "/" || part == "sqrt"
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if part == "(" {
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continue
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} else if part == ")" {
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lastOperation := operations.Pop()
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lastValue := values.Pop()
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switch lastOperation {
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case "+":
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lastValue = values.Pop() + lastValue
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case "-":
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lastValue = values.Pop() - lastValue
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case "*":
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lastValue = values.Pop() * lastValue
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case "/":
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lastValue = values.Pop() / lastValue
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case "sqrt":
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lastValue = int(math.Sqrt(float64(lastValue)))
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}
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values.Push(lastValue)
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} else if isOperation {
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operations.Push(part)
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} else {
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newValue, _ := strconv.Atoi(part)
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values.Push(newValue)
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}
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}
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return values.Pop()
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}
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