【HDU】 2709

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

题解：奇数dp[i]=dp[i-1]  偶数dp[i]=dp[i-1]+dp[i/2]

AC代码：

#include<stdio.h>

long long dp[1000000+5];int main(){long long n;dp[1]=1;dp[2]=2;for(int i=3;i<1000000+5;i++){if(i%2!=0)dp[i]=dp[i-1]%1000000000;else dp[i]=(dp[i-1]+dp[i/2])%1000000000;}while(scanf("%lld",&n)!=EOF){printf("%lld\n",dp[n]);}return 0;}