POJ2229 Sumsets 基礎DP

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<algorithm>
 4 
 5 using namespace std;
 6 
 7 const int maxn=1000000+3;
 8 
 9 #define LL long long
10 
11 LL dp[maxn];
12 const LL mod=1000000000;
13 
14 int main()
15 {
16     dp[0]=dp[1]=1;
17     for(int i=2;i<maxn;i++)
18     {
19         if(i%2)
20             dp[i]=dp[i-1];
21         else
22             dp[i]=dp[i-2]+dp[i/2];
23         while(dp[i]>=mod)
24             dp[i]-=mod;
25     }
26 
27     int N;
28     while(~scanf("%d",&N))
29     {
30         printf("%d\n",dp[N]);
31     }
32 
33     return 0;
34 }