The sword refers to the offer - the problem of the frog going up the stairs

 The bullshit sword refers to the offer- frog up the stairs problem:

         Problem description: A frog can take 1 or 2 steps at a time. How many ways can the frog jump to n steps?

         

         Problem analysis:

                There are two jumping methods in the first step: a> Assuming that the first jump is step 1, then the remaining steps are n-1 steps, and the jumping method is f(n-1);

                                                b> Assuming that the first jump is 2 steps, then the rest are n-2 steps, and the jump method is f(n-2);

                Then it can be known from a and b that the total jump method f(n)=f(n-1)+f(n-2);  

                And because when n=1, f(1)=1; when n=2, f(2)=2; we can get:

                       | 1,(n=1)

                f(n)=| 2,(n=2)

                       | f(n-1)+f(n-2) (n>2, n is an integer)

                It can be found that this is a Fibonacci sequence;

 

code show as below:

import java.util.Scanner;

/**
 * The sword refers to the offer-
 * Frog up the stairs problem:
 * A frog can go up 1 or 2 steps at a time. Find how many ways the frog can jump up to n steps.
 * @author Jiacheng
 *
 */
public class Frogwstj {
	public static void main(String[] args) {
		Frogwstj frog=new Frogwstj();
		Scanner scanner=new Scanner(System.in);
		while(true){
			int count=frog.upperStage(scanner.nextInt());
			System.out.println("Total: "+count+" methods");
		}
	}
/**
 * recursive calculation
 * @param n number of steps
 * @return the total way to go up the stairs
 */
	private int upperStage(int n) {
		if(n==1){
			return 1;
		}
		if(n==2){
			return 2;
		}
		int sum=upperStage(n-1)+upperStage(n-2);
		return sum;
		
	}
}