poj 1840 Eqs （hash）

 1 #include<cstdio>
 2  #include<string>
 3  #include<iostream>
 4  #include<cstring>
 5  #include<map>
 6  using namespace std;
 7  
 8  short hash[25000001];
 9  int main()
10  {
11      int a1,a2,a3,a4,a5;
12      int x1,x2,x3,x4,x5;
13       int sum,ans=0;
14         cin>>a1>>a2>>a3>>a4>>a5;
15          memset(hash,0,sizeof(hash));
16          for(x1=-50; x1<=50; x1++)
17          {
18              if(!x1) continue;
19              for(x2=-50; x2<=50; x2++)
20              {
21                  if(!x2) continue;
22                  sum=a1*x1*x1*x1+a2*x2*x2*x2;
23                  if(sum<0)
24                  sum+=25000000;
25                  hash[sum]++;
26              }
27          }
28          for(x3=-50; x3<=50; x3++)
29          {
30              if(!x3)  continue;
31              for(x4=-50; x4<=50; x4++)
32              {
33                  if(!x4)  continue;
34                  for(x5=-50; x5<=50; x5++)
35                  {
36                      if(!x5)  continue;
37                      sum=a3*x3*x3*x3+a4*x4*x4*x4+a5*x5*x5*x5;
38                      if(sum<0)
39                      sum+=25000000;
40                      ans+=hash[sum];
41                  }
42              }
43          }
44          cout<<ans<<endl;
45  
46      return 0;
47  }
48