結果

問題 No.308 素数は通れません
ユーザー Grenache
提出日時 2015-12-01 20:33:20
言語 Java
(openjdk 23)
結果
AC  
実行時間 81 ms / 1,000 ms
コード長 3,863 bytes
コンパイル時間 4,015 ms
コンパイル使用メモリ 80,112 KB
実行使用メモリ 37,432 KB
最終ジャッジ日時 2024-11-27 18:16:57
合計ジャッジ時間 12,230 ms
ジャッジサーバーID
（参考情報） 		judge2 / judge3
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ファイルパターン 結果
other AC * 107
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Deque;
import java.util.Iterator;
import java.util.List;
public class Main_yukicoder308_1 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        Printer pr = new Printer(System.out);
        String N = sc.next();
        if (N.length() <= 2) {
            int n = Integer.parseInt(N);
            boolean[] notprime = new boolean[n + 1];
            notprime[1] = true;
            for (int i = 2; i * i <= n; i++) {
                if (!notprime[i]) {
                    for (int j = 2; i * j <= n; j++) {
                        notprime[i * j] = true;
                    }
                }
            }
            for (int w = 2; w <= n; w++) {
                if (dfs(w, n, notprime, pr)) {
                    pr.println(w);
                    break;
                }
            }
        } else {
            int mod = 0;
            for (int i = 0; i < N.length(); i++) {
                mod = (10 * mod + (N.charAt(i) - '0')) % 8;
            }
            if (mod != 1) {
                pr.println(8);
            } else {
                if (isPrime(N, 8)) {
                    pr.println(14);
                } else {
                    pr.println(8);
                }
            }
        }
        pr.close();
        sc.close();
    }
    private static boolean isPrime(String N, int sub) {
        if (N.length() < 12) {
            long n = Long.parseLong(N);
            n -= sub;
            boolean prime = (n != 1);
            for (long i = 2; i * i <= n; i++) {
                if (n % i == 0) {
                    prime = false;
                    break;
                }
            }
            return prime;
        } else {
            BigInteger n = new BigInteger(N);
            n = n.subtract(new BigInteger(Integer.toString(sub)));
            return n.isProbablePrime(20);
        }
    }
    private static boolean dfs(int w, int n, boolean[] notprime, Printer pr) {
        int[] d = {w, 1, -1, -w};
        boolean[] used = new boolean[n + 1];
        Deque<Integer> st = new ArrayDeque<Integer>();
        Deque<List<Integer>> rt = new ArrayDeque<List<Integer>>();
        st.push(1);
        rt.push(new ArrayList<Integer>());
        used[1] = true;
        while (!st.isEmpty()) {
            int e = st.pop();
            List<Integer> tmprt = rt.pop();
            for (int i = 0; i < d.length; i++) {
                int tmp = e + d[i];
                if (tmp < 1 || tmp > n) {
                    continue;
                }
                if (e % w == 0 && d[i] == 1) {
                    continue;
                }
                if (e % w == 1 && d[i] == -1) {
                    continue;
                }
                if (tmp == n) {
                    tmprt.add(tmp);
//                  pr.println(tmprt.toString());
                    return true;
                }
                if (!used[tmp] && notprime[tmp]) {
                    used[tmp] = true;
                    st.push(tmp);
                    List<Integer> tt = new ArrayList<Integer>(tmprt);
                    tt.add(tmp);
                    rt.push(tt);
                }
            }
        }
        return false;
    }
    @SuppressWarnings("unused")
    private static class Scanner {
        BufferedReader br;
        Iterator<String> it;
        Scanner (InputStream in) {
            br = new BufferedReader(new InputStreamReader(in));
        }
        String next() throws RuntimeException  {
            try {
                if (it == null || !it.hasNext()) {
                    it = Arrays.asList(br.readLine().split(" ")).iterator();
                }
                return it.next();
            } catch (IOException e) {
                throw new IllegalStateException();
            }
        }
        int nextInt() throws RuntimeException {
            return Integer.parseInt(next());
        }
        long nextLong() throws RuntimeException {
            return Long.parseLong(next());
        }
        float nextFloat() throws RuntimeException {
            return Float.parseFloat(next());
        }
        double nextDouble() throws RuntimeException {
            return Double.parseDouble(next());
        }
        void close() {
            try {
                br.close();
            } catch (IOException e) {
//              throw new IllegalStateException();
            }
        }
    }
    private static class Printer extends PrintWriter {
        Printer(PrintStream out) {
            super(out);
        }
    }
}
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