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fibonacci.cpp
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fibonacci.cpp
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/*This file implements printing the nth fibonacci number*/
#include<iostream>
#include<map>
#include <ctime>
using namespace std;
int slowfib(int n)
{
if(n==0) return 0;
else if(n==1) return 1;
return slowfib(n-1)+slowfib(n-2);
}
int fastfib(int n)
{
static map<unsigned int, unsigned int> mapfib;
if(mapfib.count(n)>0) return mapfib[n];
if(n==0) return 0 ; else if(n == 1) return 1;
int ret = fastfib(n-1)+fastfib(n-2);
mapfib[n]=ret;
return ret;
}
int main()
{
cout<<"Please input the index of the fibonacci number you want ?";
int n;
cin>>n;
clock_t begin = clock();
cout<<"The "<<n<<"th fibonacci number through slow fn is "<< slowfib(n)<<"\n";
clock_t end = clock();
double elapsed_secs = double(end - begin) / CLOCKS_PER_SEC;
cout<<"Time elapsed for slow function "<<elapsed_secs<<"\n";
begin = clock();
cout<<"The "<<n<<"th fibonacci number through fast fn is "<< fastfib(n)<<"\n";
end = clock();
elapsed_secs = double(end - begin) / CLOCKS_PER_SEC;
cout<<"Time elapsed for fast function"<<elapsed_secs<<"\n";
return 0;
}