poj 2229 Sumsets 完全背包求方案总数

#include<stdio.h>
#include<string.h>
#define ll long long
#define mod 1000000007
#define esp 0.00000000001
const int N=1e5+10,M=1e6+10,inf=1e9;
int a[22]={1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192,16384,32768,65536,131072,262144,524288};
int dp[M];
int main()
{
    int x,y,z,i,t;
    memset(dp,0,sizeof(dp));
    dp[0]=1;
    for(i=0;i<20;i++)
    {
        for(t=a[i];t<=1000000;t++)
        dp[t]+=dp[t-a[i]],dp[t]%=inf;
    }

    while(~scanf("%d",&x))
    printf("%d\n",dp[x]);
    return 0;
}