九度 1402 特殊的数

普通的方法：

package com.wangzhu.njupt;



import java.io.BufferedInputStream;

import java.io.IOException;

import java.io.StreamTokenizer;



/**

 * 由于输入的数在1~100000之间，故只需要开个100000大小的数组，判断其是否存在即可

 * 

 * @ClassName: Main1402

 * @Description: TODO

 * @author 王竹

 * @date 2014-10-3 下午5:21:31

 * 

 */

public class Main1402 {



    private static final int LEN = 1000001;



    /**

     * @param args

     * @throws IOException

     */

    public static void main(String[] args) throws IOException {

        // System.setIn(new FileInputStream("data.in"));

        // 输入优化

        StreamTokenizer in = new StreamTokenizer(new BufferedInputStream(

                System.in));

        // Scanner cin = new Scanner(new BufferedInputStream(System.in));

        // while (cin.hasNext()) {

        while (in.nextToken() != StreamTokenizer.TT_EOF) {

            int[] arr = new int[LEN];

            // int n = cin.nextInt();

            int n = (int) in.nval;

            int m = -1;

            for (int i = 0; i < n; i++) {

                // m = cin.nextInt();

                in.nextToken();

                m = (int) in.nval;

                arr[m]++;

            }

            StringBuilder sb = new StringBuilder();

            int c = 0, index = 0;

            for (int i = 1; i < LEN; i++) {

                if (arr[i] == 1) {

                    if (index == 0) {

                        sb.append(i);

                        index = 1;

                    } else {

                        sb.append(" ").append(i);

                    }

                    c++;

                }

            }

            System.out.println(c);

            if (c > 0) {

                System.out.println(sb);

            }



        }

    }

}

位存储的方法：

package com.wangzhu.njupt;



import java.io.BufferedInputStream;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.OutputStreamWriter;

import java.io.PrintWriter;

import java.io.StreamTokenizer;

import java.util.Scanner;



public class Main14022 {



    /**

     * 用位来存储数

     */

    private static final int LEN = (1000000 >> 3) + 10;

    /**

     * 用于模8，即与7

     */

    private static final int MASK = (1 << 3) - 1;

    /**

     * 要查的数的范围为1~1000000

     */

    private static final int SIZE = 1000001;



    /**

     * @param args

     * @throws IOException

     */

    public static void main(String[] args) throws IOException {

        // System.setIn(new FileInputStream("data.in"));

        // Scanner cin = new Scanner(new BufferedInputStream(System.in));

        // 输入优化

        StreamTokenizer in = new StreamTokenizer(new BufferedInputStream(

                System.in));

        // 输出优化

        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));

        // while (cin.hasNext()) {

        while (in.nextToken() != StreamTokenizer.TT_EOF) {

            int[] arr = new int[LEN];

            int[] flag = new int[LEN];

            // int n = cin.nextInt();

            int n = (int) in.nval;

            for (int i = 0; i < n; i++) {

                // int m = cin.nextInt();

                in.nextToken();

                int m = (int) in.nval;

                // 其实是除以8

                int index = m >> 3;

                // 其实是模8

                int bit = m & MASK;

                if ((arr[index] & (1 << bit)) == 0) {

                    // 记录输入中的数

                    arr[index] |= (1 << bit);

                } else if ((flag[index] & (1 << bit)) == 0) {

                    // 记录输入多个同样的数

                    flag[index] |= (1 << bit);

                }

            }

            int cnt = 0;

            for (int i = 1; i < SIZE; i++) {

                int index = i >> 3;

                int bit = i & MASK;

                if ((arr[index] & (1 << bit)) != 0

                        && (flag[index] & (1 << bit)) == 0) {

                    // 判断是输入的数并且只输入了一次

                    // 记录这种数的个数

                    cnt++;

                }

            }

            StringBuilder sb = new StringBuilder();

            int j = 0;

            for (int i = 1; (i < SIZE) && (j < cnt); i++) {

                int index = i >> 3;

                int bit = i & MASK;

                if ((arr[index] & (1 << bit)) != 0

                        && (flag[index] & (1 << bit)) == 0) {

                    sb.append(i).append(" ");

                    j++;

                }

            }

            String ret = null;

            out.println(cnt);

            if (cnt > 0) {

                ret = sb.substring(0, sb.length() - 1);

                out.println(ret);

            }

            out.flush();

        }

    }

}

 

 

备注：

关于位运算的一些补充：

例如，

关于n/8，可以转化为n>>3。

关于n%8，可以转化为n&7，当然也已转化为n - (n>> 3)<<3。