poj 2229 Sumsets (DP)
http://poj.org/problem?id=2229
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).
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
思路很简单直接看代码:分奇数偶数
#include<iostream> #include<cstring> #include<cstdlib> using namespace std; const int MAXN=1000001; const int M=1000000000; int dp[MAXN]; int main() { int N; while(cin>>N){ dp[0]=dp[1]=1; for(int i=2;i<=N;i++){ if( i&1 ) dp[i]=dp[i-1]; else dp[i]=(dp[i-2]+dp[i>>1])%M; } cout<<dp[N]<<endl; } return 0; }