Submission #3773115

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Source Code Expand

import java.util.Arrays;
import java.util.InputMismatchException;
import java.util.Scanner;

public class Main{

    /**
     * 全体処理
     * @param args
     */
    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
       
        int n = 0;
        n = input();
        calc(n);
    }

    /**
     * 計算
     * @param n
     * @throws Exception
     */
    private static void calc(int n) throws Exception {
        // TODO Auto-generated method stub
        boolean flag = true;
        double pi = Math.PI;
        //System.out.println(flag);
        Scanner sc = null;
        int[] c = new int[n];
        try {
            sc = new Scanner(System.in);
            int i = 0;
            while (i < n) {
               // System.out.println("第"+(i+1)+"番の円を入力してください：　　");
                c[i] = sc.nextInt();
                i++;
            }

        } catch (InputMismatchException e) {
            System.out.println("error");
        } finally {
            sc.close();
        }

        Arrays.sort(c);
        // nは奇数、偶数を判断する
        if (n % 2 == 0) {
            flag = false;
        }
        double sum_r =0,sum_w=0;
        double menseki_r=0,menseki_w=0;
        
        if (flag = true)// 奇数の場合
        {
           // System.out.println("円の数が奇数");
            for(int i=0;i<n;i++)
            {
                if(i%2==0)
                {
                  //  System.out.println(i+"番偶数");
                    menseki_r = Math.pow(c[i], 2)*pi;
                    //System.out.println("面積赤"+menseki_r);
                    sum_r = sum_r + menseki_r;
                     
                }
                else
                {
                    //System.out.println(i+"番奇数");
                    menseki_w = Math.pow(c[i], 2)*pi;
                    //System.out.println("面積白"+menseki_w);
                    sum_w = sum_w + menseki_w;                    
                }
                
            }
           //System.out.println("赤い部分面積:"+Math.abs(sum_r - sum_w));    
            System.out.println(Math.abs(sum_r - sum_w));    
            
        } else if (flag = false)// 偶数の場合
        {
            //System.out.println("円の数が偶数");
            for(int i=0;i<n;i++)
            {
                if(i%2!=0)
                {
                    menseki_r = Math.pow(c[i], 2)*pi;
                    sum_r = sum_r + menseki_r;
                     
                }
                else
                {
                    menseki_r = Math.pow(c[i], 2)*pi;
                    sum_w = sum_w + menseki_w;                    
                }
                
            }
           //System.out.println("赤い部分面積:"+Math.abs(sum_r - sum_w)); 
            System.out.println(Math.abs(sum_r - sum_w)); 

        } else {
            throw new Exception("input error calc");
        }

    }

    /**
     * 入力処理
     * @return
     */
    private static int input() {
        // TODO Auto-generated method stub
        Scanner sc = null;
        
            sc = new Scanner(System.in);
            //System.out.println("円の数を入力してください：");
            int n;
            n = sc.nextInt();
            return n;
      

    }

}

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