九度 1349 数字在排序数组中出现的次数

 

package com.wangzhu.njupt;



import java.io.BufferedInputStream;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.StreamTokenizer;



/**

 * 在已排序的数组中查找数出现的次数

 * 

 * @ClassName: Main1349

 * @Description: TODO

 * @author 王竹

 * @date 2014-10-5 下午5:02:27

 * 

 */

public class Main1349 {



    private static final int LEN = 1000001;

    private static int[] arr = new int[LEN];



    /**

     * @param args

     * @throws IOException

     */

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

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

        StreamTokenizer in = new StreamTokenizer(new BufferedInputStream(

                System.in));

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

            int n = (int) in.nval;

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

                in.nextToken();

                arr[i] = (int) in.nval;

            }

            in.nextToken();

            int t = (int) in.nval;

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

                in.nextToken();

                int m = (int) in.nval;

                int index = binarySearch(n, m);

                int count = 0;

                if (index != -1) {

                    count++;

                    int j = index - 1;

                    while (j >= 0 && arr[j--] == m) {

                        count++;

                    }

                    j = index + 1;

                    while (j < n && arr[j++] == m) {

                        count++;

                    }

                }

                System.out.println(count);

            }

        }

    }



    /**

     * 二分查找

     * 

     * @param len

     * @param key

     * @return

     */

    private static int binarySearch(int len, int key) {

        int left = 0, right = len - 1;

        while (left <= right) {

            int mid = (left + right) >> 1;

            if (arr[mid] > key) {

                right = mid - 1;

            } else if (arr[mid] < key) {

                left = mid + 1;

            } else {

                return mid;

            }

        }

        return -1;

    }



}