HDU1496HASH

Problem Description

Consider equations having the following form:

a*x1^2+b*x2^2+c*x3^2+d*x4^2=0
a, b, c, d are integers from the interval [-50,50] and any of them cannot be 0.

It is consider a solution a system ( x1,x2,x3,x4 ) that verifies the equation, xi is an integer from [-100,100] and xi != 0, any i ∈{1,2,3,4}.

Determine how many solutions satisfy the given equation.

 

Input

The input consists of several test cases. Each test case consists of a single line containing the 4 coefficients a, b, c, d, separated by one or more blanks.
End of file.

 

Output

For each test case, output a single line containing the number of the solutions.

 

Sample Input

   
   
   
   

    
    
    
    1 2 3 -4
1 1 1 1
   
   
   
   

 

Sample Output

   
   
   
   

    
    
    
    39088
0
   
   
   
   
   
   
   
   

    
    
    
    HASH(1)
   
   
   
   
   
   
   
   

    
    
    
    
#include <stdio.h>
#include <iostream>
#include <string.h>
using namespace std;
const int maxn=1000005;
int vis[2000005];
int main()
{
    int a,b,c,d;
    while(~scanf("%d%d%d%d",&a,&b,&c,&d))
    {
        if(a>0&&b>0&&c>0&&d>0)
        {
            printf("0\n");
            continue;
        }
        int ans=0;
        memset(vis,0,sizeof(vis));
        for(int i=1;i<=100;i++)
            for(int j=1;j<=100;j++)
                vis[i*i*a+b*j*j+maxn]++;
        for(int i=1;i<=100;i++)
            for(int j=1;j<=100;j++)
                ans+=vis[-(c*i*i+d*j*j)+maxn];
        printf("%d\n",ans*16);
    }
    return 0;
}
   
   
   
   
   
   
   
   

    
    
    
     
   
   
   
   
   
   
   
   

    
    
    
    HASH(2)
   
   
   
   
   
   
   
   

    
    
    
    
#include <stdio.h>
#include <iostream>
#include <string.h>
using namespace std;
const int maxn = 50001;

int num[maxn],s[maxn];

int hash(int x){
    int tmp=x%maxn;
    if(tmp<0) tmp+=maxn;
    while(num[tmp]!=0&&s[tmp]!=x)
        tmp=(tmp+1)%maxn;
    return tmp;
}
int main(){
    int tmp,cur,a,b,c,d;
    while(cin>>a>>b>>c>>d){
        if((a>0&&b>0&&c>0&&d>0)||(a<0&&c<0&&d<0&&b<0)){
            cout<<"0"<<endl;
            continue;
        }
        memset(num,0,sizeof(num));
        for(int i=1;i<=100;i++){
            for(int j=1;j<=100;j++){
                int x=a*i*i+b*j*j;
                tmp=hash(x);
                s[tmp]=x;
                num[tmp]++;
            }
        }
        int ans=0;
        for(int i=1;i<=100;i++){
            for(int j=1;j<=100;j++){
                int x=-(c*i*i+d*j*j);
                tmp=hash(x);
                ans+=num[tmp];
            }
        }
        cout<<ans*16<<endl;
    }
}