poj 1840 Eqs （hash）

题目：http://poj.org/problem?id=1840

题解：http://blog.csdn.net/lyy289065406/article/details/6647387 小优姐讲的很好了

 #include<cstdio>
  #include<string>
  #include<iostream>
  #include<cstring>
  #include<map>
  using namespace std;

  short hash[];
  int main()
  {
      int a1,a2,a3,a4,a5;
      int x1,x2,x3,x4,x5;
       int sum,ans=;
         cin>>a1>>a2>>a3>>a4>>a5;
          memset(hash,,sizeof(hash));
          for(x1=-; x1<=; x1++)
          {
              if(!x1) continue;
              for(x2=-; x2<=; x2++)
              {
                  if(!x2) continue;
                  sum=a1*x1*x1*x1+a2*x2*x2*x2;
                  if(sum<)
                  sum+=;
                  hash[sum]++;
              }
          }
          for(x3=-; x3<=; x3++)
          {
              if(!x3)  continue;
              for(x4=-; x4<=; x4++)
              {
                  if(!x4)  continue;
                  for(x5=-; x5<=; x5++)
                  {
                      if(!x5)  continue;
                      sum=a3*x3*x3*x3+a4*x4*x4*x4+a5*x5*x5*x5;
                      if(sum<)
                      sum+=;
                      ans+=hash[sum];
                  }
              }
          }
          cout<<ans<<endl;

      return ;
  }