public class Demo2 { 
  // 定義三個變量方法 
  public static void main(String[] args) { 
    int a = 1, b = 1, c = 0; 
    System.out.println("斐波那契數(shù)列前20項為："); 
    System.out.print(a + "\t" + b + "\t"); 
    //因為前面還有兩個1、1 所以i<=18 
    for (int i = 1; i <= 18; i++) { 
      c = a + b; 
      a = b; 
      b = c; 
      System.out.print(c + "\t"); 
      if ((i + 2) % 5 == 0) 
        System.out.println(); 
    } 
  } 
 
} 

public class Demo3 { 
  // 定義數(shù)組方法 
  public static void main(String[] args) { 
    int arr[] = new int[20]; 
    arr[0] = arr[1] = 1; 
    for (int i = 2; i < arr.length; i++) { 
      arr[i] = arr[i - 1] + arr[i - 2]; 
    } 
    System.out.println("斐波那契數(shù)列的前20項如下所示："); 
    for (int i = 0; i < arr.length; i++) { 
      if (i % 5 == 0) 
        System.out.println(); 
      System.out.print(arr[i] + "\t"); 
    } 
  } 
 
} 

public class Demo4 { 
  // 使用遞歸方法 
  private static int getFibo(int i) { 
    if (i == 1 || i == 2) 
      return 1; 
    else 
      return getFibo(i - 1) + getFibo(i - 2); 
  } 
 
  public static void main(String[] args) { 
    System.out.println("斐波那契數(shù)列的前20項為："); 
    for (int j = 1; j <= 20; j++) { 
      System.out.print(getFibo(j) + "\t"); 
      if (j % 5 == 0) 
        System.out.println(); 
    } 
  } 
 
}