java初级问题

1.纯随机数发生器

public class suijishu
{
        private static final int N = 200;
        private static final int LEFT = 40;
        private static final int RIGHT = 1000;
        private static long x0 = 1L;
        private long a = 1103515245L;
        private long c = 12345L;
        private long m = 2147483648L;
            private long rand ( long r )
            {
              r = ( r * a + c ) % m;                                              
          return r;
        }
        private long little ( int a, int b, long rand )
        {
          return a + rand % ( b - a + 1 );
        }
        private void recursion ( int count, long rand )    
        {
         if (count >= N)
         {return;}
         rand = rand (rand);
         long r = little (LEFT, RIGHT, rand);
         System.out.println (r);
         recursion (++count, rand);
        }
        public static void main ( String[] args )
        {
        suijishu recur = new suijishu ();
         recur.recursion (0, x0);
        }
}

2.当函数的形参类型不同时，函数可以重载。

3.组合数计算

import java.util.Scanner;
public class zuheshu1 {
    public static int jiecheng(int x){
        int m=1;
    if(x<0) {
        System.out.println("输入错误");
        System.exit(0);
    }
    else if(x==0||x==1)
        m=1;
    else 
        m=jiecheng(x-1)*x;
    return m;
    }
    public static int jszhs1(int k,int n){
    int c=jiecheng(n)/(jiecheng(k)*jiecheng(n-k));
    return c;
    }
    public static int jszhs2(int n,int k) {
    int i=1;
       int c=1;
    for(i=k;k<n;i++) {
        c=c*(i/(i+k))*jszhs1(k,i-1);
    }
    return c;
    }
    public static int jszhs3(int k,int n) {
        int c=1;
        if(k==n) {return c;}
        else {return (n/(n-k))*jszhs3(k,n-1);}
    }
    public static void main(String args[]) {
        System.out.print("请选择组合数运算方法：1组合数公式；2递推杨辉三角；3递归");
        Scanner sc=new Scanner(System.in);
        int d=sc.nextInt();
        System.out.print("请输入组合数中的k和n：");
        int a=sc.nextInt();
        int b=sc.nextInt();
        switch(d) {
        case 1:System.out.println("结果为："+jszhs1(a,b));break;
        case 2:System.out.println("结果为："+jszhs2(a,b));break;
        case 3:System.out.println("结果为："+jszhs3(a,b));break;
        }
    }
}

4.汉诺塔问题

import java.util.Scanner;
public class hannuota {
    public static void yidong(int panzi,int kaishi,int zhongjian,int zuihou) {
        if(panzi==1) {
            System.out.println(kaishi+"-->"+zhongjian);
            return;
        }
        yidong(panzi-1,kaishi,zuihou,zhongjian);    
        System.out.println(kaishi+"-->"+zhongjian);
        yidong(panzi-1,zuihou,zhongjian,kaishi);
    
    }
    public static void main(String args[]) {
        System.out.println("请输入盘子数：");
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        System.out.println("移动方法为：");
        yidong(n,1,3,2);
    }

}

5.回文字符串

import java.util.Scanner;
class huiwen {
    public static int panduan(String s) {
        int length=s.length();
        if(length==0||length==1)
            return 1;
        char first=s.charAt(0);
        char last=s.charAt(length-1);
        if(first!=last)
            return 0;
        return panduan(s.substring(1, length-1));
    }
    public static void main(String args[]) {
        Scanner sc=new Scanner(System.in);
        System.out.println("请输入一个字符串：");
        String s=sc.nextLine();
        if(panduan(s)==1) System.out.println("是回文字符串");
        else System.out.println("不是回文字符串");
    }

}