题解 | #计算一元二次方程#

import java.util.Scanner;
public class Main{
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        while(scan.hasNextDouble()) {
            double aValue = scan.nextDouble();
            double bValue = scan.nextDouble();
            double cValue = scan.nextDouble();
            if(aValue == 0.0) {//a=0,没有根
                System.out.println("Not quadratic equation");
            } else {//有根
                double delta = Math.pow(bValue, 2) - 4 * aValue * cValue;
                double real = - bValue / (2 * aValue);
                if(delta > 0.0) {//两个互异实数根
                    double image = Math.sqrt(delta) / (2 * aValue);
                    System.out.printf("x1=%.2f;x2=%.2f\n", real - image, real + image);
                } else if(delta < 0.0) {//两个互异复数根
                    double image = Math.sqrt( -delta) / (2 * aValue);
                    System.out.printf("x1=%.2f-%.2fi;x2=%.2f+%.2fi\n", real, image, real, image);
                } else {//两个相同根
                    System.out.printf("x1=x2=%.2f\n", real);
                }
            }
        }
    }
}