lm-tecniche-di-programmazione/src/main/kotlin/it/norangeb/algorithms/exam/Equations.kt

73 lines
2.3 KiB
Kotlin

/*
* MIT License
*
* Copyright (c) 2019 norangebit
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
*/
package it.norangeb.algorithms.exam
import java.lang.Exception
import java.util.Stack
object Equations {
fun compute(equation: String): Double {
val operator = Stack<Operations>()
val operandi = Stack<Double>()
equation.split(" ").forEach {
when (it) {
"+" -> operator.push(Operations.PLUS)
"-" -> operator.push(Operations.MINUS)
"*" -> operator.push(Operations.PER)
")" -> operandi.push(
canculate(operator.pop(), operandi.pop(), operandi.pop())
)
else -> {
try {
operandi.push(it.toDouble())
} catch (e: Exception) {
println("error, $e")
}
}
}
}
return operandi.pop()
}
private fun canculate(
op: Operations,
d1: Double,
d2: Double
): Double {
println("$d1, $op, $d2")
return when (op) {
Operations.PLUS -> d1 + d2
Operations.MINUS -> d2 - d1
Operations.PER -> d1 * d2
}
}
}
enum class Operations {
PLUS, MINUS, PER
}