hdu 1028 整数划分 （母函数）

假如输入4
4 = 4;
4 = 3 + 1;
4 = 2 + 2;
4 = 2 + 1 + 1;
4 = 1 + 1 + 1 + 1;
一共5种

假如输入3 用母函数的方法就是写成
（1+X+X2+X3）(1+X2)(1+X3) 展开后 求X3的系数

假如输入n
就是（1+X+X2+X3+X4....）(1+X2+X4+X6..)(1+X3+X6...)(....)

Sample Input
4
10
20

Sample Output
5
42
627

 1 # include <iostream>
 2 # include <cstdio>
 3 # include <cstring>
 4 # include <algorithm>
 5 # include <string>
 6 # include <cmath>
 7 # include <queue>
 8 # include <list>
 9 # define LL long long
10 using namespace std ;
11
12 int c1[10010], c2[10010] ;
13 int main()
14 {
15     //freopen("in.txt","r",stdin) ;
16     int nNum;
17     int i, j, k;
18
19     while(cin >> nNum)
20     {
21         for(i=0; i<=nNum; ++i)
22         {
23             c1[i] = 1;
24             c2[i] = 0;
25         }
26         for(i=2; i<=nNum; ++i)
27         {
28
29             for(j=0; j<=nNum; ++j)
30                 for(k=0; k+j<=nNum; k+=i)
31                 {
32                     c2[j+k] += c1[j];
33                 }
34                 for(j=0; j<=nNum; ++j)
35                 {
36                     c1[j] = c2[j];
37                     c2[j] = 0;
38                 }
39         }
40         cout << c1[nNum] << endl;
41     }
42     return 0;
43 }