BlogJava-Be alaways javaing...-随笔分类-数据结构与算法

二分搜索法

追风舞者 — Fri, 10 Oct 2008 08:19:00 GMT

public class Search {

    /**
     * 前提条件array数组已排序
     */
    public static boolean binarySearch(int[] array, int target) {
        boolean result = false;
        int bottom = 0;
        int top = array.length-1;
        while (bottom <= top) {
            int mid = (top + bottom) / 2;
            if (target == array[mid]) {
                result = true;
                break;
            } else if (target < array[mid]) {
                top = mid - 1;
            } else if (target > array[mid]) {
                bottom = mid + 1;
            }
        }

        return result;
    }

    public static void main(String[] args) {
        int [] array = {1,3,5,7,9,10};
        boolean result = binarySearch(array, 10);
        System.out.println(result);
    }
}

追风舞者 2008-10-10 16:19 发表评论

汉诺塔

追风舞者 — Fri, 10 Oct 2008 07:56:00 GMT

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Hanoi {
    public static void main(String[] args) throws NumberFormatException,
            IOException {
        System.out.print("请输入盘数：");
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());
        move(n, 'A', 'B', 'C');
    }

    /**
     * 将n个盘子借助b，从 a 移到 c
     */
    public static void move(int n, char a, char b, char c) {
        if (n == 1)
            System.out.println("盘 " + n + " 由 " + a + " 移至 " + c);
        else {
            move(n - 1, a, c, b);
            System.out.println("盘 " + n + " 由 " + a + " 移至 " + c);
            move(n - 1, b, a, c);
        }
    }
}

追风舞者 2008-10-10 15:56 发表评论

Java快速排序

追风舞者 — Fri, 10 Oct 2008 07:39:00 GMT

public class Sort {

    public static void quickSort(int[] array) {
        quickSort(array, 0, array.length - 1);
    }

    private static void quickSort(int[] array, int low, int high) {
        if (low < high) {
            int p = partition(array, low, high);
            quickSort(array, low, p - 1);
            quickSort(array, p + 1, high);
        }

    }

    private static int partition(int[] array, int low, int high) {
        int s = array[high];
        int i = low - 1;
        for (int j = low; j < high; j++) {
            if (array[j] < s) {
                i++;
                swap(array, i, j);
            }
        }
        swap(array, ++i, high);
        return i;
    }

    private static void swap(int[] array, int i, int j) {
        int temp;
        temp = array[i];
        array[i] = array[j];
        array[j] = temp;
    }

    public static void main(String[] args) {
        int [] array = {2,5,3,7,4};
        quickSort(array);
        for(int i = 0;i<array.length;i++){
            System.out.println(array[i]);
        }
    }

}

追风舞者 2008-10-10 15:39 发表评论