用大数加法模板计算很大的斐波那契数列

计算很大的斐波那契数列


#include<iostream>
#include<cstdio>
#include<string>
using namespace std;
const int INF=5000;
string p[INF];
string sum(string s1,string s2)
{
if(s1.length()<s2.length())
{
string temp=s1;
s1=s2;
s2=temp;
}
int i,j;
for(i=s1.length()-1,j=s2.length()-1;i>=0;i--,j--)
{
s1[i]=char(s1[i]+(j>=0?s2[j]-'0':0));
if(s1[i]-'0'>=10)
{
s1[i]=char((s1[i]-'0')%10+'0');
if(i) s1[i-1]++;
else s1='1'+s1;
}
}
return s1;
}
int main()
{
int n;
cin>>n;
p[0]="0"; p[1]="1";
for(int i=2;i<=n;i++)
p[i]=sum(p[i-1],p[i-2]);
cout<<p
<<endl;
return 0;
}