Binary tree

SwiftBinarytree.swift

import Foundation

class ClassNode {
    var value: Double?
    var operation: String?
    var leftChild: ClassNode?
    var rightChild: ClassNode?
    
    init(value: Double? = nil, operation: String? = nil, leftChild:ClassNode? = nil, rightChild: ClassNode? = nil) {
        self.value = value
        self.operation = operation
        self.leftChild = leftChild
        self.rightChild = rightChild
    }
    
    func evaluate() -> Double {
        if let op = operation {
            guard let leftChild = leftChild else { fatalError("no left child in binary operation") }
            guard let rightChild = rightChild else { fatalError("no right child in binary operation") }
            switch op {
            case "+":
                return leftChild.evaluate() + rightChild.evaluate()
            case "-":
                return leftChild.evaluate() - rightChild.evaluate()
            case "*":
                return leftChild.evaluate() * rightChild.evaluate()
            case "/":
                return leftChild.evaluate() / rightChild.evaluate()
            case "^":
//                var value =  rightChild.evaluate()
//                let sum = leftChild.evaluate()
//                while (value > 1) {
//                    value -= 1
//                    sum * leftChild.evaluate()
//                }
//                return sum
                return pow(leftChild.evaluate(), rightChild.evaluate())
            default:
                fatalError("Undefined operation")
            }
        } else {
            guard let value = value else { fatalError("No value provided") }
            return value
        }
    }
}


let formula = ClassNode(operation: "+", leftChild: ClassNode(operation: "*", leftChild: ClassNode(value: 2), rightChild: ClassNode(value: 3)), rightChild: ClassNode(value: 4))
print(formula.evaluate())

let BMIformula = ClassNode(operation: "/", leftChild: ClassNode(value: 88), rightChild: ClassNode(operation: "^", leftChild: ClassNode(value: 1.90), rightChild: ClassNode(value: 2)))
print(BMIformula.evaluate())