[C language series] - a recursive topic

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*  Blog column ：【C All living things 】*

Introduction to this article ： Simply tear a recursive topic by hand ！

Get to know the author ： Aspire to be a great programmer , Xiaobai, who is currently a sophomore in College .

Inspirational terms ： The tediousness of programming , Let's study together and become interesting ！

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List of articles

Preface

subject

Ideas

Graphic process

Conclusion  

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Preface

In a scene yesterday C In the preliminary language examination , Fortunately, I came across a problem about recursion , The problem I couldn't do at that time , But with years of guessing experience , Very lucky to guess the right answer ！

subject

After the following procedure is executed , What is the result of the output ？

​
#include<stdio.h>
int cnt = 0;
int fib(int n)
{
	cnt++;
	if (n == 0)
		return 1;
	else if (n == 1)
		return 2;
	else
		return fib(n - 1) + fib(n - 2);
}
int main()
{
	fib(8);
	printf("%d", cnt);
	return 0;
}

​

Ideas

To write this problem, you must understand the concept and usage of recursive functions ！

Now let's analyze this problem ：

1. Global variables are defined cnt Used to count , Every time you call a function ,cnt Meeting ++ once , The main function passes a 8 Get into fib() function ;

After analysis, this problem actually requires to find out that when the transmission parameter is 8 when , Called fib() The number of functions ！

2. Drawing pictures is more conducive to solving problems ！

Graphic process

Let's run it to see if 67 Time ！

Conclusion  

well ！ This is the end of my sharing today , If you think it helps , You can pay attention to bloggers ！ Bloggers will update regularly ！