笔头练习

//输入一个值 查找对应数组中元素的索引
import java.util.Scanner;

public class Test06 {
    public static void main(String[] args) {
        int[] arr = {19, 28, 37, 46, 50};
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入查找的数据： ");
        int number = sc.nextInt();

        /*int index = -1;
        for(int x = 0; x<arr.length; x++){
            if(arr[x] == number){
                index = x;
                break;
            }
        } */
        int index = getIndex(arr, number);
        System.out.println("index: " + index);
    }

    /*方法调用2个明确：
        返回值类型：int
        参数：int[] arr,int number
     */
    public static int getIndex(int[] arr, int number) {
        int index = -1;
        for (int x = 0; x < arr.length; x++) {
            if (arr[x] == number) {
                index = x;
                break;
            }
        }
        return index;
    }
}



//用方法 判断数组是否相同
public class Test01 {
    public static void main(String[] args) {
        int[] arr = {11,22,33,44,55,66};
        int[] arr2 = {11,22,33,44,55,66};

        boolean flag = compare(arr,arr2);
        System.out.println(flag);

    }
    public static boolean compare(int[] arr, int[] arr2){
        if(arr.length != arr2.length){
            return false;
        }
        for(int x = 0; x<arr.length; x++){
            if(arr[x] != arr2[x]){
                return false;
            }
        }
        return true;
    }
}


//百钱百鸡
//一个公鸡5钱，一个母鸡3钱，一钱买3个小鸡，，共有100文钱
public class Test03 {
    public static void main(String[] args) {
        for (int x = 0; x <= 20; x++) {
            for (int y = 0; y <= 33; y++) {
                int z = 100 - x - y;

                if (z % 3 == 0 && 5 * x + 3 * y + z / 3 == 100) {
                    System.out.println(x + "," + y + "," + z);
                }

            }
        }
    }
}


//不死兔
public class Test04 {
    public static void main(String[] args) {
        int[] arr = new int[20];
        arr[0] = 1;
        arr[1] = 1;

        for(int x=2; x<arr.length;x++){
             arr[x] = arr[x-2] + arr[x - 1];
        }
        System.out.println("第二十个月兔子的对数： " + arr[19]);

    }
}


//求数组中数据 个位 十位都不能为7 且能被2整除的数据的和
public class Test02 {
    public static void main(String[] args) {
        int[] arr = {68,27,95,88,171,996,51,210};
        int sum = 0;

        for(int x = 0; x<arr.length; x++){
            if(arr[x]%10!=7 && arr[x]/10%10!=7 && arr[x]%2 == 0){
                sum += arr[x];
            }
        }
        System.out.println("sum: " + sum);
    }
}


//1-100之间逢七过
public class Test05 {
    public static void main(String[] args) {
        for(int x = 1;x <= 100;x++){
            if(x%10==7 || x/10%10==7 || x%7 ==0)
                System.out.println(x);
        }
    }
}