# POJ 1840 Eqs （哈希）

Eqs

 Time Limit: 5000MS Memory Limit: 65536K Total Submissions: 16200 Accepted: 7953

Description

Consider equations having the following form:
a1x13+ a2x23+ a3x33+ a4x43+ a5x53=0
The coefficients are given integers from the interval [-50,50].
It is consider a solution a system (x1, x2, x3, x4, x5) that verifies the equation, xi∈[-50,50], xi != 0, any i∈{1,2,3,4,5}.Determine how many solutions satisfy the given equation.

Input

The only line of input contains the 5 coefficients a1, a2, a3, a4, a5, separated by blanks.

Output

The output will contain on the first line the number of the solutions for the given equation.

Sample Input

37 29 41 43 47

Sample Output

654

### AC 代码

#include<iostream>
#include<algorithm>
#include<stdio.h>
#include<string.h>
#include<math.h>
#include<iostream>
using namespace std;
#include<queue>
#include<map>

#define MAXN 25000010

typedef __int64 LL;

int a1,a2,a3,a4,a5;
short hash[MAXN];
int main()
{
while(~scanf("%d%d%d%d%d",&a1,&a2,&a3,&a4,&a5))
{
int ans=0,temp;
for(int i=-50; i<=50; i++)
for(int j=-50; j<=50; j++)
{
if(i==0||j==0)continue;
temp=-(a1*i*i*i+a2*j*j*j);
if(temp<0)temp+=MAXN;
hash[temp]++;
}
for(int i=-50; i<=50; i++)
for(int j=-50; j<=50; j++)
for(int k=-50; k<=50; k++)
{
if(i==0||j==0||k==0)continue;
temp=a3*i*i*i+a4*j*j*j+a5*k*k*k;
if(temp<0)temp+=MAXN;
if(hash[temp])
ans+=hash[temp];
}
printf("%d\n",ans);
}
return 0;
}