ICPC 2005, Tokyo Region, Problem A

A.java

package jp.ac.oka_pu.icpc2005tokyo;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

public class A {

	class Prime {
		public int n;
		public int sum;
		public Prime(int n, int sum) {
			this.n = n;
			this.sum = sum;
		}
	}
	
	Prime[] primes;
	
	public A() {
		boolean isPrime[] = new boolean[10001];
		int primeNumber = 0;
		for (int i = 2; i < 10001; i ++) {
			isPrime[i] = true;
		}
		for (int i = 2; i < 10001; i ++) {
			if (isPrime[i]) {
				primeNumber ++;
				int k = 2;
				while (i * k <= 10000) {
					isPrime[i * k] = false;
					k ++;
				}
			}
		}
		primes = new Prime[primeNumber];
		int sum = 0;
		for (int i = 2, j = 0; i < 10001; i ++) {
			if (isPrime[i]) {
				sum += i;
				primes[j ++] = new Prime(i, sum);
			}
		}
	}
	
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		A a = new A();
		a.calc(args[0]);
	}

	public void calc(String file) {
			BufferedReader br;
			int n;
			try {
				br = new BufferedReader(new FileReader(file));
				n = Integer.parseInt(br.readLine());
				while (n != 0) {
					System.out.println(countSums(n));
					n = Integer.parseInt(br.readLine());
				};
				br.close();
			} catch (FileNotFoundException e) {
				e.printStackTrace();
			} catch (NumberFormatException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			}
	}
	
	public int countSums(int n) {
		int count = 0;
		for (int i = primes.length - 1; i >= 0 && primes[i].sum >= n; i --) {
			if (primes[i].sum == n) {
				count ++;
			} else {
				int difference = primes[i].sum - n;
				for (int j = 0; primes[j].sum <= difference; j ++) {
					if (primes[j].sum == difference) {
						count ++;
					}
				}
			}
		}
		return count;
	}
}

A00.txt

2
3
17
41
20
666
12
53
0