Tiling

 f(n) = 2 * f(n -2) + f(n - 1)

高精度运算应用

#include <iostream>#include <cstring>#include <cmath>#include <cstdio>using namespace std;struct numtype{    int len,a[100];}dp[252];int n;void add(numtype a,numtype b,numtype &c){    int i,len=max(a.len,b.len);    for(i=1;i<=len;i++)        c.a[i]=a.a[i]+b.a[i];    for(i=1;i<=len;i++)        if(c.a[i]>9)    {        c.a[i]-=10;        c.a[i+1]++;    }    if(c.a[len+1]!=0) c.len=len+1;    else c.len=len;}void cheng(numtype &x) {     int i;     for (i=1;i<=x.len;i++)         x.a[i]*=2;     for (i=1;i<=x.len;i++)         if (x.a[i]>9) {                       x.a[i]-=10;                       x.a[i+1]++;         }     if (x.a[x.len+1]!=0) x.len++;}int main(){    int i;    while(cin>>n)    {        memset(dp,0,sizeof(dp));        dp[0].len=1;        dp[0].a[1]=1;        dp[1].len=1;        dp[1].a[1]=1;        for(i=2;i<=n;i++)        {            cheng(dp[i-2]);            add(dp[i-2],dp[i-1],dp[i]);        }        for(i=dp[n].len;i>=1;i--)        {            cout<<dp[n].a[i];        }          cout<<endl;    }}