public class TeseDemo220424 {
//    計(jì)算某一個(gè)數(shù)的階乘
    public static int func(int n){
        int ret = 1;
        for(int i = 1;i <= n;i++){
            ret *= i;
        }
        return ret;
    }
//    計(jì)算前多少項(xiàng)階乘之和
    public static int func1(int k){
        int sum = 0;
        for(int i = 1;i <= k;i++){
            sum += func(i);
        }
        return sum;
    }
    public static void main(String[] args) {
//        寫函數(shù)來求階乘之和
        Scanner myscanner = new Scanner(System.in);
        System.out.println("請(qǐng)輸入你想要求取前多少項(xiàng)的階乘的和:");
        int num = myscanner.nextInt();
        int sum = func1(num);
        System.out.println("前 " + num + "項(xiàng)的階乘和為" + sum);
    }
}

public class TestDemo220426 {
    public static int addInt(int x,int y){
        return x + y;
    }
    public static double addDouble(double x,double y){
        return x + y;
    }
    public static void main(String[] args) {
        int a = 10;
        int b = 10;
        int ret = addInt(a,b);

        double c = 11.1;
        double d = 12.1;
        double ret1 = addDouble(c,d);
    }
}

public class TestDemo220426 {
    public static int add(int x,int y){
        return x + y;
    }
    public static double add(double x,double y){
        return x + y;
    }
    public static void main(String[] args) {
        int a = 10;
        int b = 10;
        int ret = add(a,b);
        System.out.println(ret);
        double c = 11.1;
        double d = 12.1;
        double ret1 = add(c,d);
        System.out.println(ret1);
    }
}

    public static  int func(int num){
        if(num == 1){
            return 1;
        }
        return num*func(num - 1);
    }
    public static void main(String[] args) {
//        遞歸求階乘
        Scanner scan = new Scanner(System.in);
        System.out.println("請(qǐng)輸入一個(gè)數(shù)：");
        int num = scan.nextInt();
        int ret = func(num);
        System.out.println("階乘為：" + ret);
    }
}

public class TestDemo220427 {
    public static void myprint(int num){
        if(num < 10){
            System.out.println(num%10);
            return;
        }
        myprint(num/10);
        System.out.println(num%10);
        return;
    }
    public static void main(String[] args) {
//        遞歸實(shí)現(xiàn)按順序打印數(shù)字的每一位
        Scanner scan = new Scanner(System.in);
        System.out.println("請(qǐng)輸入一個(gè)數(shù)：");
        int num = scan.nextInt();
        myprint(num);
    }
}

public class TestDemo220428 {
    public static int fib1(int n){
        int f1 = 1;
        int f2 = 1;
        int f3 = 1;
        for(int i = 3;i <= n;i++){
            f3 = f1 + f2;
            f1 = f2;
            f2 = f3;
        }
        return f3;
    }
    public static int fib(int n){
        if(n == 1 || n == 2){
            return 1;
        }
        return fib(n-1) + fib(n-2);
    }
    public static void main(String[] args) {
//        遞歸求斐波那契數(shù)列的第n項(xiàng)
        Scanner scan = new Scanner(System.in);
        System.out.println("請(qǐng)輸入您想要求取的項(xiàng)數(shù)：");
        int n = scan.nextInt();
        int ret = fib1(n);
        System.out.println("第" + n + "項(xiàng)為：" + ret);
    }
}