Three Methods of Recursive Fibonacci Sequence java

In this paper, we share the specific code of the Fibonacci sequence of java recursion for your reference. The specific content is as follows

The first kind, ordinary writing method

public class Demo { 
 
  public static void main(String[] args) { 
    int num1 = 1; 
    int num2 = 1; 
    int num3 = 0; 
    System.out.println(num1); 
    System.out.println(num2); 
    for (int i = 1; i < 10; i++) {  
      num3 = num1 + num2; 
      num1 = num2;                                                          
      num2 = num3; 
      System.out.println(num3); 
    } 
  }            
} 

The second, array form of recursive writing

public class DIGUI1 { 
  
  public static void main(String[] args) { 
    int []arr=new int[20]; 
     arr[1]=1; 
     arr[2]=1; 
     System.out.print(" "+arr[1]); 
     System.out.print(" "+arr[2]); 
    for(int i=3;i<20;i++){ 
       arr[i]=arr[i-1]+arr[i-2]; 
      System.out.print("  "+arr[i]); 
    } 
  } 
 } 

The third, recursive form of writing

public class Demo { 
 
  public static int f(int n) throws Exception { 
    if(n==0){ 
      throw new Exception(" Parameter error! "); 
    } 
    if (n == 1 || n == 2) { 
      return 1; 
    } else { 
      return f(n-1)+f(n-2);// Self call  
    } 
 } 
 
 
  public static void main(String[] args) throws Exception { 
    for (int i = 1; i <=10; i++) { 
      System.out.print(f(i)+" "); 
    } 
  }  
} 

The biggest problem with recursion is efficiency, but some programs must be written recursively to write them. For example, the famous Hanotta problem, if anyone can write it in a different way.