HDU 4651 数论 partition 求自然数的拆分数

别人的解题报告：

http://blog.csdn.net/zstu_zlj/article/details/9796087

我的代码：

 1 #include <cstdio>
 2 #define N 100020
 3 const int mod = 1e9+7;
 4 int p[N];
 5 void Partition()
 6 {
 7     p[0] =1;
 8     for(int n=1; n <= 1e5; ++n)
 9     {
10         int fac = 1;
11         int  k =1;
12         while(true)
13         {
14             int t=n-k*(3*k-1)/2;
15             if(t < 0) break;
16             p[n] = (p[n]+fac*p[t])%mod;
17             if(t-k >= 0)
18                 p[n] = (p[n]+fac*p[t-k])%mod;
19             p[n] %= mod;
20             fac = -fac;
21             ++k;
22         }
23         p[n] = (p[n]+mod)%mod;
24     }
25 }
26 int main()
27 {
28 //    freopen("in.cpp","r",stdin);
29     Partition();
30     int d;
31     scanf("%d",&d);
32     while(d--)
33     {
34         int c;
35         scanf("%d",&c);
36         printf("%d\n",p[c]);
37     }
38     return 0;
39 }

View Code

认真考虑二维的情况；n<10^3才可行，而且该代码没有取模操作······

我的代码：

 1 #include <cstdio>
 2 #include <cstring>
 3 #define N 2005
 4 //#define debug
 5 int d[N][N];
 6 void init()
 7 {
 8     for(int i=0; i<N; ++i)
 9         d[0][i] = d[1][i]=d[i][0]=d[i][1] =1;
10     for(int i=2; i<N; ++i)
11     {
12         for(int j=2; j<N; ++j)
13         {
14             if(i-j >= 0) d[i][j] += d[i-j][j];
15             d[i][j] += d[i][j-1];
16         }
17     }
18 }
19 int main()
20 {
21 #ifdef debug
22     freopen("in.c","r",stdin);
23 #endif
24     init();
25     int t;
26     scanf("%d",&t);
27     while(t--)
28     {
29         int m;
30         scanf("%d",&m);
31         printf("%d\n",d[m][m]);
32     }
33 
34     return 0;
35 }