HDU 2709 Sumsets

题目地址：​​点击打开链接​​

AC代码：

#include <iostream>
#include <cstring>
#include <cstdio>

using namespace std;

long long a[1000010];

int main()
{
    int i,n;
    a[1] = 1;
    a[2] = 2;
    for(i=3; i<=1000000; i++)
    {
        if(i % 2 == 1)
            a[i] = a[i-1];
        else
            a[i] = (a[i/2] + a[i-2]) % 1000000000;//开始把MXA赋为1e10，老是错误，就直接写数字了
    }
    while(~scanf("%d",&n))
    {
        printf("%I64d\n",a[n]);
    }
    return 0;
}