HDU 4671 Partition(定理题)

题目链接

这题，明显考察搜索能力。。。在中文版的维基百科中找到了公式。

 #include <cstdio>
 #include <cstring>
 #include <string>
 #include <algorithm>
 using namespace std;
 #define MOD 1000000007
 #define LL __int64
 LL dp[];
 int que[],flag[];
 int main()
 {
     int i,n,t,j,num;
     LL x;
     num = ;
     for(i = ;;i ++)
     {
         t = (*i*i - i)/;
         if(t > ) break;
         flag[num] = i;
         que[num++] = t;
         t = (*i*i + i)/;
         flag[num] = i;
         que[num++] = t;
     }
     dp[] = ;dp[] = ;
     dp[] = ;
     for(i = ;i <= ;i ++)
     {
         for(j = ;j <= ;j ++)
         {
             if(que[j] > i)
             break;
             else
             x = dp[i-que[j]];
             if(flag[j]% == )
             {
                 dp[i] = (dp[i] + x)%MOD;
             }
             else
             {
                 dp[i] = (dp[i] - x)%MOD;
                 if(dp[i] < )
                 dp[i] += MOD;
             }
         }
     }
     scanf("%d",&t);
     while(t--)
     {
         scanf("%d",&n);
         printf("%I64d\n",dp[n]);
     }
     return ;
 }