prod()方法在此Java程序中做什么? [英] What does the method prod() do in this Java program?

问题描述

public class Prod {

public static void main(String[] args) {
    System.out.println(prod(1, 4));
}

public static int prod(int m, int n) {
    if (m == n) {
        return n;
    } else {
        int recurse = prod(m, n-1);
        int result = n * recurse;
        return result;
    }
}
}

这是我受难的书中的一项练习.为什么程序不只是递归直到两个数字相等然后返回n?另外，它说的是

This is an exercise in the book I am stumped on. Why would the program not just recurse until the two numbers are equal and then return n ? Also, where it says,

int result = n * recurse;

它如何将int n乘以递归，即(int, int)?如何将一个整数乘以两个整数?

How does it multiply int n by recurse which would be (int, int)? How can it multiply one integer by a set of two integers?

我以什么方式误解了该程序?

In what way am I misunderstanding this program?

这是一个不同的问题，因为我没有使用阶乘

This is a different question because I am not using factorials

推荐答案

prod(x,y)在x=1时等效于y!. 如果x与1不同，则对其进行递归乘法(y * (y- 1) * (y -2) .... )直到y = x. 假设y > x.

prod(x,y) is equivalent to y! when x=1. If x is different from 1, then its doing recursive multiplication (y * (y- 1) * (y -2) .... ) until y = x. Assuming y > x.

顺便说一句，如果x > y然后prod()将会崩溃.

By the way, if x > y then prod() will crash.

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