[Blue] entry Bridge Cup title

Find the area of ​​a circle

Involving knowledge points

java accuracy

Code

package 圆的面积;
import java.text.DecimalFormat;
import java.util.Scanner;

import static java.lang.StrictMath.atan;

public class Main{
    public static void main(String[] args){
        double PI=atan(1.0)*4;
        Scanner read =new Scanner(System.in );
        int r= read.nextInt();
        double area= PI*r*r;
        //Java中规定精确度
        DecimalFormat df = new DecimalFormat("#0.0000000");
        System.out.println(df.format(area));
    }
}

Fibonacci number

Design knowledge

Fibonacci number, take the remainder

Code

package Fibonacci数列;
import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in=new Scanner(System.in);
		int n=in.nextInt();
		int []f=new int[1000000];
		f[1]=1;
		f[2]=1;
		for(int i=3;i<=n;i++)
		{
			f[i]=(f[i-1]+f[i-2])%10007;
		}
		System.out.println(f[n]);
	}

}

Sequence summing

Seeking 1 + 2 + 3 + 4 + ...... + n

Involving knowledge points

data range

Code

import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in=new Scanner(System.in);
		long n=in.nextInt();
		long m=n*(n+1)/2;
		System.out.println(m);

	}

}

A + B problem

Code

import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in=new Scanner(System.in);
		int a=in.nextInt();
		int b=in.nextInt();
		System.out.println(a+b);
	}

}