ACM Lab 1 Task 7

import acm.program.ConsoleProgram;

public class Task7 extends ConsoleProgram {
    int recursiveSteps = 0;
    int recurrentSteps = 0;

    public void run() {
        print("This program calculates e^x with the provided x and accuracy level.\n\n");
        double x;
        while (true) {
            x = readDouble("Enter the value of x: ");
            if (x < 0 || x >= 1) {
                print("The value of x should be in the range of [0, 1)\n");
            } else {
                break;
            }
        }

        double accuracy;
        while (true) {
            accuracy = readDouble("Enter accuracy level: ");
            if (accuracy <= 0) {
                print("The value of accuracy should be >0\n");
            } else {
                break;
            }
        }

        print("\n");

        double recursiveRes = recursiveSum(x, 0, accuracy);

        print("Recursive: " + recursiveRes + "\nSteps done: " + recursiveSteps);
        print("\n\n");

        double recurrentOldValue = 0;
        double recurrentRes = 0;

        while (true) {
            recurrentRes += recurrentSum(x);
            if (Math.abs(recurrentRes - recurrentOldValue) < accuracy) {
                break;
            }
            recurrentOldValue = recurrentRes;
        }
        print("Recurrent: " + recurrentRes + "\nSteps done: " + recurrentSteps);
    }

    private double recurrentSum(double x) {
        double res = Math.pow(x, recurrentSteps)/factorial(recurrentSteps);
        recurrentSteps++;
        return res;
    }

    private double recursiveSum(double x, double old_value, double accuracy) {
        double res = Math.pow(x, recursiveSteps)/factorial(recursiveSteps);
        recursiveSteps++;
        if (x == 0) {
            return 1;
        } else if (Math.abs(res - old_value) < accuracy) {
            return res;
        } else {
            return res + recursiveSum(x, res, accuracy);
        }
    }

    private int factorial(int number) {
        if (number <= 1) {
            return 1;
        } else {
            return number * factorial(number - 1);
        }
    }
}