基础算法

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冒泡排序（一）；

public class DoubleSort{
    public static void main(String[] args){
        int[] ints = {1,2,4,9,8,7,6,5,4,3};
        doubleSort(ints);
    }
    public static void doubleSort(int[] vlaue){
        int temp;
        for(int i = 0;i<value.length;i++){
            for(int j= 0;j<value.length-1-i;j++){
                if(value[j+1]<value[j]){
                    temp = value[j];
                    value[j] = value[j+1];
                    value[j+1] = temp;
                }
            }
        }
    }
}

二分查找：

public class BinarySearch{
    public static void main(String[] args){
        int ints = {9,2,3,4,5,7,8,1,6,0};
        int searchWord = 6;
        Arrays.sort(ints);
        Arrays.toString(ints);
        System.out.println("查找元素的索引是："+binarySearch(ints,searchWord));
    }
    public static int binarySearch(int[] array,int value){
        int low = 0 ;
        int high = array.length-1;
        whille(low >= high){
            //写成（low+high）/2会数组越界导致内存溢出
            int middle = low + (high -low)/2;
            if(value == array[middle]){
                return middle;
            }
            if(value > array[middle]){
                low = middle +1;
            }
            if(value < array[middle]){
                high = midddle -1;
            }
        }
        return -1;
    }
}

数组逆序：

public class Test{
    public static void main(String[] args){
        int[] ints = {0,9,8,7,6,5,4,3,2,1};
        Arrays.toString(ints);
        for(int i = 0;i < (int)ints.length/2;i++){
            int temp = ints[i];
            ints[ints.length-i-1] = ints[i];
            ints[i] = temp;
        }
        for(int i:ints){
            System.out.println(i);
        }
    }
}

使用递归算法，以树状结构展示目录树

public class PrintFile(){
    public static void main(String[] args){
        //录入文件夹名称
        File file = new file("willem")
        //调用遍历打印目录树的方法
        printFile(file,0);
    }
    static void printFile(File file,int level){
        //遍历层次
        for(int i = 0;i<level;i++){
            System.out.print("-");
        }
        //输出文件名称
        System.out.println(file.getName());
        //声明存放File[]
        if(file.isDirectory()){
            File[] file = file.listFiles();
            for(File file1 : file){
                ///递归调用该方法：注意层级+1
                printFile(file1,level+1);
            }
        }
        
    }
}