POJ 2229 Sumsets

Sumsets

Time Limit: 2000MS		Memory Limit: 200000K
Total Submissions: 11892		Accepted: 4782

Description

Farmer John commanded his cows to search for different sets of numbers that sum to a given number. The cows use only numbers that are an integer power of 2. Here are the possible sets of numbers that sum to 7:

1) 1+1+1+1+1+1+1 
2) 1+1+1+1+1+2 
3) 1+1+1+2+2 
4) 1+1+1+4 
5) 1+2+2+2 
6) 1+2+4

Help FJ count all possible representations for a given integer N (1 <= N <= 1,000,000).

Input

A single line with a single integer, N.

Output

The number of ways to represent N as the indicated sum. Due to the potential huge size of this number, print only last 9 digits (in base 10 representation).

Sample Input

7

Sample Output

6

Source

USACO 2005 January Silver

 

#include <cstdio>
int a[1000005];
int mod=1e9;
int dp[355][355];
int main ()
{int i,n;
a[1]=1;
a[2]=2;
for(i=3;i<=1000000;i++)
if(i&1) a[i]=a[i-1];
else a[i]=(a[i-2]+a[i>>1])%mod;
while(~scanf("%d",&i))
{
printf("%d\n",a[i]);
}
return 0;
}

好经典的题目。居然a[2]忘记给值了~