Submission #111487

---

Source Code Expand

import java.util.Scanner;

public class Main {

	/** コンストラクタ */
	public Main(){
	}
	
	private double length(Point a,Point b){
		double ans = 1.0;
		
		ans *= Math.sqrt((b.x - a.x)*(b.x - a.x) + (b.y - a.y)*(b.y - a.y));
		
		return ans;
	}

	/** mainメソッド */
	public static void main(String[] args) {
		Main main = new Main();
		Scanner scan = new Scanner(System.in);
		Point[] pointArray = new Point[3];
		double[] lengthArray = new double[3];
		
		for(int i=0;i<pointArray.length;i++){
			int x = scan.nextInt();
			int y = scan.nextInt();
			pointArray[i] = main.new Point(x,y);
		}
		
		lengthArray[0] = main.length(pointArray[0], pointArray[1]);
		lengthArray[1] = main.length(pointArray[1], pointArray[2]);
		lengthArray[2] = main.length(pointArray[2], pointArray[0]);
		double s = (lengthArray[0] + lengthArray[1] + lengthArray[2]) / 2;
		double ans = Math.sqrt(s * (s-lengthArray[0]) * (s-lengthArray[1]) * (s-lengthArray[2]));
		
		System.out.println(ans);
	}
	
	/** 座標クラス */
	private class Point{
		private int x;
		private int y;
		
		/** コンストラクタ */
		private Point(int x, int y){
			this.x = x;
			this.y = y;
		}
	}
}

Submission Info

Judge Result