array-ArrayDemo01-08

package com.kuang.array;
//=====================
//Demo01
//=====================
public class ArrayDome01 {
    //变量的类型 变量的名字 = 变量的值;
    //数组类型

    public static void main(String[] args) {

        int[] nums;//1.生命一个数组

//      int nums2[];//C语言写法

        nums = new int[10]; //2.创建一个个数组

        //3.给数组元素中赋值
        nums[0] = 1;
        nums[1] = 2;
        nums[2] = 3;
        nums[3] = 4;
        nums[4] = 5;
        nums[5] = 6;
        nums[6] = 7;
        nums[7] = 8;
        nums[8] = 9;
        nums[9] = 10;

//        System.out.println(nums[9]);

        //计算所有元素的和
        int sum = 0;
        for (int i = 0; i < nums.length; i++) {
            sum = sum + nums[i];
        }

        System.out.println("总和为: "+sum);

    }
}

package com.kuang.array;
//=====================
//Demo02
//=====================
public class ArrayDemo02 {
    public static void main(String[] args) {
        //静态初始化
        int [] a = {1, 2, 3, 4, 5, 6, 7, 8};
        System.out.println(a[0]);

        for (int i = 0; i < a.length; i++) {
            System.out.println(a[i]);
        }

        //动态初始化
//        int[] b = new int[10];
//        b[0] = 10;
//        b[1] = 10;
//        System.out.println(b[0]);
//        System.out.println(b[1]);
//        System.out.println(b[2]);
//        System.out.println(b[3]);
    }
}

package com.kuang.array;
//=====================
//Demo03
//=====================
public class ArrayDemo03 {
    public static void main(String[] args) {
        int[]  arrays = {1, 2, 3, 4, 5};

        //打印全部的数组元素
        for (int i = 0; i < arrays.length; i++) {
            System.out.println(arrays[i]);
        }

        System.out.println("=================");

        //计算所有元素的和
        int sum = 0;
        for (int i = 0; i < arrays.length; i++) {
            sum+= arrays[i];
        }
        System.out.println("sum="+sum);
        System.out.println("=================");

        //查找最大元素
        int max = arrays[0];

        for (int i = 0; i < arrays.length; i++) {
            if (arrays[i]>max){
                max = arrays[i];
            }
        }
        System.out.println("max="+max);

    }
}

package com.kuang.array;
//=====================
//Demo04
//=====================
public class ArrayDemo04 {
    public static void main(String[] args) {
        int[] arrays = {1, 2, 3, 4, 5};

//        //JDK1.5    没有下标
//        for (int array : arrays){
//            System.out.println(array);
//        }

//        printArray(arrays);
          int[] reverse = reverse(arrays);
          printArray(reverse);
    }


    //反转数组
    public static int[] reverse(int[] arrays){
        int[] result = new int [arrays.length];

        //反转的操作
        for (int i = 0, j = result.length-1; i <arrays.length ; i++, j--) {
            result[j] = arrays[i];
        }
        return  result;
    }


    //打印数组元素
    public static void printArray(int[] arrays){
        for (int i = 0; i < arrays.length; i++) {
            System.out.print(arrays[i]+" ");
        }
    }

}

package com.kuang.array;
//=====================
//Demo05
//=====================
public class ArrayDemo05 {
    public static void main(String[] args) {

        //[4][2]
        /*
            1, 2    array[0]
            2, 3    array[1]
            3, 4    array[2]
            4, 5    array[3]
         */
        int [][] array = {{1,2}, {2,3}, {3,4}, {4,5}};

        printArray(array[0]);
        System.out.println("\n"+"===============");

        for (int i = 0; i < array.length; i++) {
            for (int j = 0; j < array[i].length; j++) {
                System.out.print(array[i][j]+" ");
            }
            System.out.println();
        }
    }

    public static void printArray(int[] arrays){
        for (int i = 0; i < arrays.length; i++) {
            System.out.print(arrays[i]+ " ");

        }
    }
}

package com.kuang.array;
//=====================
//Demo06
//=====================
import java.util.Arrays;

public class ArrayDemo06 {
    public static void main(String[] args) {

        int[] a = {1, 2, 3, 4, 9090, 31231, 543, 21, 3, 23};

        //System.out.println(a);  //[I@154617c
        //打印数组元素Arrays.toString
        //System.out.println(Arrays.toString(a));
        //printArray(a);

        Arrays.sort(a); //数组进行排序 : 升序
        System.out.println(Arrays.toString(a));

        Arrays.fill(a, 2,4,0);//数组填充
        System.out.println(Arrays.toString(a));
    }

    public static void printArray(int[] a){
        for (int i = 0; i < a.length; i++) {
            if (i==0){
                System.out.print("[");
            }
            if (i==a.length-1){
                System.out.print(a[i] + "]");
            }else {
                System.out.print(a[i] + ", ");

            }
        }
    }
}

 

package com.kuang.array;
//=====================
//Demo07
//=====================
import java.util.Arrays;

//冒泡排序
//1.比较数组中, 两个相邻的元素, 如果第一个数比第二个数大, 我们就交换它们的位置
//2.每一次比较, 都会产生出一个最大,胡总二号最小的数字;
//3.下一轮则可以少一次排序!
//4.依次循环, 直到结束!
public class ArrayDemo07 {
    public static void main(String[] args) {
        int[] a = {1, 4, 5, 6, 72, 2, 2, 2, 25, 6, 7};
        int[] sort = sort(a);
        System.out.println(Arrays.toString(sort));


    }


    public static int[] sort(int[] array){
        //临时变量
        int temp = 0;

        //外层循, 判断我们这个要走多少次;
        for (int i = 0; i < array.length-1; i++) {

            boolean flag = false; //通过flag标识位减少没有意义的比较

            //内层循环, 比价判断两个数, 比第二个数大, 则交换位置
            for (int j = 0; j < array.length-1-i; j++){
                if (array[j+1] < array[j]){
                    temp = array[j];
                    array[j] = array[j+1];
                    array[j+1] = temp;
                    flag = true;
                }
            }

            if (flag == false){
                break;
            }

        }

        return array;
    }
}

package com.kuang.array;
//=====================
//Demo08
//=====================
public class ArrayDemo08 {
    public static void main(String[] args) {
        //1. 创建一个二维数组 11*11     0:没有棋子  1:黑棋    2:白棋
        int[][] array1 = new int[11][11];
        array1[1][2] = 1;
        array1[2][3] = 2;
        //输出原始的数组
        System.out.println("输出原始的数组");

        for (int[] ints : array1){
            for (int anInt : ints){
                System.out.print(anInt + "\t");
            }
            System.out.println();
        }

        //转换为稀疏数组来保存
        //获取有效值的个数
        int sum = 0;
        for (int i = 0; i < 11; i++) {
            for (int j = 0; j < 11; j++) {
                if (array1[i][j] != 0){
                    sum++;
                }
            }
        }
        System.out.println("有效值的个数" + sum);

        //2.创建一个稀疏数组的数组
        int[][] array2 = new int[sum+1][3];

        array2[0][0] = 11;
        array2[0][1] = 11;
        array2[0][2] = sum;

        //便利二维数组, 将非零的值, 存放在稀疏数组中
        int count = 0;
        for (int i = 0; i < array1.length; i++) {
            for (int j = 0; j < array1[i].length; j++) {
                if (array1[i][j] != 0){
                    count++;
                    array2[count][0] = i;
                    array2[count][1] = j;
                    array2[count][2] = array1[i][j];
                }
            }
        }

        //输出稀疏数组
        System.out.println("稀疏数组");

        for (int i = 0; i < array2.length; i++) {
            System.out.println(array2[i][0] + "\t"
                        +array2[i][1] + "\t"
                        +array2[i][2] + "\t");

        }

        System.out.println("=================");
        System.out.println("还原");

        //1.读取稀疏数组
        int[][] array3 = new int[array2[0][0]][array2[0][1]];

        //2.给其中的元素还原它的值
        for (int i = 1; i < array2.length; i++){
            array3[array2[i][0]][array2[i][1]] = array2[i][2];
        }

        //3.打印
        System.out.println("输出还原的数组");

        for (int[] ints : array1){
            for (int anInt : ints){
                System.out.print(anInt + "\t");
            }
            System.out.println();
        }
    }
}