recfib.cpp

来自「C++&datastructure书籍源码,以前外教提供现在与大家共享」· C++ 代码 · 共 30 行

#include <iostream>
using namespace std;
#include "prompt.h"

// Illustrates "bad" recursion for computing  Fibonacci numbers
// and a global variable to count # function calls

int gFibCalls = 0;

long RecFib(int n)
// precondition: 0 <= n
// postcondition: returns the n-th Fibonacci number
{
    gFibCalls++;
    if (0 == n || 1 == n)
    {   return 1;
    }
    else
    {   return RecFib(n-1) + RecFib(n-2);
    }
}

int main()
{
    int num = PromptRange("compute Fibonacci #",1,40);
    cout << "Fibonacci # " << num << " = " << RecFib(num) << endl;
    cout << "total # function calls = " << gFibCalls << endl;
    return 0;
}