选择冒泡排序，二分查找法以及一些for循环的灵活运用

Posted 2020-09-24 雲淡、風輕

import java.util.Arrays;
//冒泡排序
public class Test {

    public static void main(String[] args) {
        int[] array = { 31, 22, 15, 77, 52, 32, 18, 25, 16, 7 };
        // 冒泡 --> 两两比较  -->  提取出最大的数  在最后一位 
　　　   //拿第一位和它后面的一位进行 两两比较
        System.out.println(Arrays.toString(array));
        for (int j = 0; j < array.length; j++) {
            for (int i = 0; i < array.length - 1 - j; i++) {
                // 如果前面的数大于后面的数 交换位置
                if (array[i] < array[i + 1]) {
                    int temp = array[i];
                    array[i] = array[i + 1];
                    array[i + 1] = temp;
                }
            }
        }
        System.out.println(Arrays.toString(array));
    }
}

import java.util.Arrays;
//选择排序
public class Test {

    public static void main(String[] args) {
        int[] array = { 31, 22, 15, 77, 52, 32, 18, 25, 16, 7 };
        // 选择 --> 第一位与后面所有的数字进行比较 
        System.out.println(Arrays.toString(array));
        for (int i = 0; i < array.length; i++) {
            for (int j = i + 1; j < array.length; j++) {
                if (array[i] < array[j]) {
                    // 如果 array[0]比array[1]大，交换位置
                    // 第三方变量temp
                    int temp = array[i];
                    array[i] = array[j];
                    array[j] = temp;
                }
            }
        }
        System.out.println(Arrays.toString(array));
    }
}

 

import java.util.Arrays;
import java.util.Scanner;

//  二分查找  折半查找法    从中间斩断，比较值。继续比较
public class Test11 {

    public static void main(String[] args) {
        // 二分查找法 插入排序
        int[] array = { 3, 10, 15, 22, 33, 51, 77, 88 };
        System.out.println(Arrays.toString(array));
        Scanner input = new Scanner(System.in);
        do {

            System.out.print("输入需要插入的数据:");
            int number = input.nextInt();
　　　　　　　// 每次获取最左边的数和最右边的数  
            int left = 0;
            int right = array.length - 1;
            int result = recursion(array, left, right, number);
            System.out.println(result);
            int[] newArray = new int[array.length + 1];
            for (int i = 0; i < newArray.length; i++) {
                if (i < result) {
                    newArray[i] = array[i];
                } else if (i == result) {
                    newArray[i] = number;
                } else {
                    newArray[i] = array[i - 1];
                }
            }
            array = newArray;
            System.out.println(Arrays.toString(array));
        } while (true);
    }

        //递归
    public static int recursion(int[] array, int left, int right, int number) {
        // 如果大于右边，或者小于左边
        if (array[0] > number)
            return 0;
        else if (array[array.length - 1] < number)
            return array.length;
　　　　 　
        int center = (left + right) / 2;
        if (left == right - 1)
            return right;
        if (array[center] > number) {
            return recursion(array, left, center, number);
        } else {
            return recursion(array, center, right, number);
        }
    }

}

//for循环打印矩形
public class Rect {

    public void show(int width, int height) {

        for (int i = 0; i < width; i++) {
            for (int j = 0; j < height; j++) {
                if (i == 0 || j == 0 || i == width - 1 || j == height - 1)
                    System.out.print("*");
                else
                    System.out.print(" ");
            }
            System.out.println();
        }
    }
}

//for循环打印菱形
public class Rhombus {

    public void show(int height) {
        int half = height / 2;
        for (int i = 1; i <= half; i++) {
            // 先打空格
            for (int j = half - i + 1; j > 0; j--) {
                System.out.print(" ");
            }
            for (int j = 0; j < 2 * i - 1; j++) {
                System.out.print("*");
            }
            System.out.println();
        }

        for (int i = 0; i < 2 * half + 1; i++) {
            System.out.print("*");
        }
        System.out.println();

        for (int i = 1; i <= half; i++) {
            // 先打空格
            for (int j = i; j > 0; j--) {
                System.out.print(" ");
            }
            for (int j = 0; j < 2 * (half - i) + 1; j++) {
                System.out.print("*");
            }
            System.out.println();
        }
    }

}

//for循环打印等腰三角形
public class Isosceles {

    public void show(int height) {
        for (int i = 1; i <= height; i++) {
            // 先打空格
            for (int j = height - i; j > 0; j--) {
                System.out.print(" ");
            }
            for (int j = 0; j < 2 * i - 1; j++) {
                System.out.print("*");
            }
            System.out.println();
        }
    }
}

//for循环打印之间三角形
public class Triangle {

    public void show(String str, int height) {
        for (int i = 0; i < height; i++) {
            for (int j = 0; j < i + 1; j++) {
                System.out.print(str);
            }
            System.out.println();
        }
    }

}