UVA 580(p331)----Critical Mass

#include<iostream>#include<cstdio>#include<cmath>using namespace std;const int maxn=30+5;int f[maxn],g[maxn];void prepare(){    f[0]=0;f[1]=0;    f[2]=0;f[3]=1;    g[0]=1;g[1]=2;    g[2]=4;g[3]=7;    for(int i=3;i<=30;i++)    {        int tmp=0;        for(int k=2;k<=i-2;k++)            tmp+=g[k-2]*pow(2,i-k-2);        f[i]=pow(2,i-3)+tmp;        g[i]=pow(2,i)-f[i];    }}int main(){    int n;    prepare();    while(scanf("%d",&n)==1&&n)        printf("%d\n",f[n]);    return 0;}

题目地址： https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=521