2021年07月03日 09:27

이준우

edited: 2021年07月14日 11:10

C#

using System;
using System.Numerics;
namespace 허근까지
{
 class Program
 {
 static void Main()
 {
 var solution = new QuadraticEquation(1, 4, 5);
 Console.WriteLine(solution);
 }
 }
 class QuadraticEquation
 {
 private readonly double quadraticCoeff, linearCoeff, constantCoeff;
 public QuadraticEquation(double quadraticCoeff, double linearCoeff, double constantCoeff)
 {
 this.quadraticCoeff = quadraticCoeff; // 2차항 계수
 this.linearCoeff = linearCoeff; // 1차항 계수
 this.constantCoeff = constantCoeff; // 상수항 계수
 this.Discriminant = Math.Pow(linearCoeff, 2.0) - 4.0 * this.quadraticCoeff * this.constantCoeff;
 }
 // 판별식
 public double Discriminant { get; }
 // 해를 문자열 표현으로 반환
 public override string ToString()
 {
 Complex solution1 = (-linearCoeff + Complex.Sqrt(Discriminant)) / (2.0 * quadraticCoeff);
 Complex solution2 = (-linearCoeff - Complex.Sqrt(Discriminant)) / (2.0 * quadraticCoeff);
 string expression1 = Complex2Expression(solution1);
 string expression2 = Complex2Expression(solution2);
 return Discriminant == 0 ? $"{expression1}" : $"{expression1}, {expression2}";
 }
 // 복소수 클래스를 문자열 표현으로 변환
 private static string Complex2Expression(Complex complex)
 {
 // 해의 정수 반올림
 int realValue = (int)Math.Round(complex.Real);
 int imagValue = (int)Math.Round(complex.Imaginary);
 // 해를 경우따른 문자열로 표현
 string first = realValue != 0 ? $"{realValue}" : "";
 string sign = imagValue < 0 ? "-" : "+";
 string second = Math.Abs(imagValue) != 1 ? $"{Math.Abs(imagValue)}i" : "i";
 if (imagValue == 0)
 {
 second = string.Empty;
 sign = string.Empty;
 }
 string expression = $"{first}{sign}{second}";
 if (expression == "")
 {
 expression = "0";
 }
 return expression;
 }
 }
}

using System;
namespace solution
{
 class Program
 {
 static void Main(string[] args)
 {
 Console.WriteLine("이차방정식 ax2 + bx + c = 0 에서 a b c 을 입력하세요.(예: 1 -3 2)");
 string[] coeff = Console.ReadLine().Split(' ');
 Console.WriteLine("{0}x2 + {1}x + {2} = 0 의 해: {3}",coeff[0], coeff[1], coeff[2], solution(coeff));
 }
 private static string solution(string[] coeff)
 {
 string ans = "";
 double a = double.Parse(coeff[0]);
 double b = double.Parse(coeff[1]);
 double c = double.Parse(coeff[2]);
 double D = b * b - 4 * a * c;
 string strD = "";
 if (D < 0)
 {
 int rootD = (int)Math.Round(Math.Sqrt(-D) / (2 * a));
 strD = rootD == 1 ? "i" : rootD.ToString() + "i";
 if (-b / (2 * a) == 0)
 ans = strD + " , -" + strD;
 else
 ans = Math.Round(-b/(2*a)) + " + " + strD + " , " + Math.Round(-b / (2 * a)) + " - " + strD;
 }
 else if (D > 0)
 {
 double dd = Math.Sqrt(D) / (2 * a);
 Console.WriteLine(-b / (2 * a) + " : "+ dd);
 ans = Math.Round((-b - Math.Sqrt(D)) / (2 * a)).ToString() + " , " + Math.Round((-b + Math.Sqrt(D)) / (2 * a)).ToString();
 }
 else
 ans = Math.Round(-b/(2*a)).ToString();
 return ans;
 }
 }
}