遞歸在java中

Question

鑑於這種方法調用：

public class MainClass { 

public static void main(String[] args) { 
    System.out.println(fib(3)); 
} 

private static int fib(int i) { 
    System.out.println("Into fib with i = " + i); 

    if (i < 2) { 
     System.out.println("We got here"); 
     return i; 
    } 
    return fib(i-1) + fib(i-2); 
} 

} 

我預計：

* fib(i-1) to return 2 
* fib(i-2) to return 1 
* return 2 + 1 to return 3 

結果：

2 

這是控制檯輸出：

Into fib with i = 3 
Into fib with i = 2 
Into fib with i = 1 
We got here 
Into fib with i = 0 
We got here 

我明白了一切到這部分：

Into fib with i = 0 

何時能拿到我曾經去過0？

Answer 1

fib(3)來電fib(2)。當您撥打fib(2)時，它將撥打fib(i-1)和fib(i-2)，即fib(1)和fib(0)。