poj1840

题意：给出ai（i=1～5），求a1 * x1^3+ a2 * x2^3+ a3 * x3^3+ a4 * x4^3+ a5 * x5^3=0在－50到50之间的x的解的个数

分析：用map，二重循环枚举x1,x2计算结果在map中对应位＋＋

三重循环枚举x3,x4,x5计算结看map中对应的相反数的个数。

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <map>
usingnamespace std;

int a[6];
map<int, int> h;

int main()
{
    //freopen("t.txt", "r", stdin);
for (int i =1; i <6; i++)
        scanf("%d", &a[i]);
    for (int i =-50; i <=50; i++)
        for (int j =-50; j <=50; j++)
        {
            if (i ==0|| j ==0)
                continue;
            int temp = i * i * i * a[1] + j * j * j * a[2];
            if (h.find(temp) == h.end())
                h[temp] =1;
            else
                h[temp]++;
        }
    int ans =0;
    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;
                int temp = i * i * i * a[3] + j * j * j * a[4] + k * k * k
                        * a[5];
                if (h.find(0- temp) == h.end())
                    continue;
                ans += h[0- temp];
            }
    printf("%d\n", ans);
    return0;
}