POJ题目1840 Eqs（hash）

Eqs

Time Limit: 5000MS		Memory Limit: 65536K
Total Submissions: 12949		Accepted: 6349

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

Source

Romania OI 2002

用int超内存

ac代码

#include<stdio.h>
#include<string.h>
short hash[25000020];
int sum;
int a,b,c,d,e;
void sol()
{
int i,j,k;
memset(hash,0,sizeof(hash));
for(i=-50;i<=50;i++)
for(j=-50;j<=50;j++)
for(k=-50;k<=50;k++)
{
if(i==0||j==0||k==0)
continue;
int res=a*i*i*i+b*j*j*j+c*k*k*k;
if(res<0)
res+=25000000;
hash[res]++;
}
}
void fun()
{
int i,j;
for(i=-50;i<=50;i++)
for(j=-50;j<=50;j++)
{
if(i==0||j==0)
continue;
int res=d*i*i*i+e*j*j*j*-1;
if(res<0)
res=25000000+res;
sum+=hash[res];
}
}
int main()
{
//	int a,b,c,d,e;
while(scanf("%d%d%d%d%d",&a,&b,&c,&d,&e)!=EOF)
{
int i,j,k;
sum=0;
sol();
fun();
printf("%d\n",sum);
}
}