简单的递归示例-请帮助我理解递归 [英] simple recursive example - please help me understand recursion

问题描述

    public static int triple(int n)
    {
        if (n == 0)
            return 0;
        else
            total = 3 + triple(n-1);
    System.out.println(total);
    return total;
    }

好吧，所以我有一个我似乎无法理解的简单的示例，我希望有人能够帮助我逐步了解程序如何获取输出.

Ok, so I've got this simple recusion example that I just cant seem to grasp, I was hoping someone would be kind enough to walk me through cycle by cycle of how the program gets its output.

这就是我认为会发生的事情.可以说n=5 因此，程序循环并命中total = 3 + triple(5-1) 我认为这等于7.这是错误的 程序打印

Here is what I thought would happen. Lets say n=5 So, the program cycles and hits total = 3 + triple(5-1) which i would think would be equal to 7.. which is wrong the program prints

3
6
9
12
15

3
6
9
12
15

所以...然后我认为三元组必须在打印总计之前再次运行...我相信确实如此，但我只是不明白那时的总计如何.

So... then I thought triple must run through again before printing the total... which I believe it does but I just don't understand how it comes to its totals at all then.

因为它看起来像这样:

3 + triple(4)
       3 + triple(3)
               3 + triple(2)
                       3 + triple(1)
                                =3

有人可以请你解释一下，因为我很迷茫！

Can someone explain please, as you can I am very lost!

推荐答案

您在解释它时略有错误.像这样:

You're interpreting it slightly wrong. It's more like this:

triple(5) = 3 + triple(4)
triple(4) = 3 + triple(3)
triple(3) = 3 + triple(2)
triple(2) = 3 + triple(1)
triple(1) = 3 + triple(0)
triple(0) = 0

现在想象triple(0)，triple(1)等都是单独的变量，并通过逐步解决来解决triple(5).

Now imagine that triple(0), triple(1), etc. are all individual variables, and solve for triple(5) by working your way up.

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