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  • Eqs 哈希

                                                       Eqs

    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

    #include<stdio.h>
    #include<string.h>
    short a[12500001], b[12500001];
    int main()
    {
        int a1, a2, a3, a4, a5, ans=0, i, j;
        scanf("%d%d%d%d%d", &a1, &a2, &a3, &a4, &a5);
        memset(a, 0, sizeof(a));
        memset(b, 0, sizeof(b));
        for(i=-50; i<=50; i++)
            for(j=-50; j<=50; j++)
            {
                if(i==0 || j==0)
                    continue;
                int sum = a1*i*i*i + a2*j*j*j;
                if(sum <= 0)
                    a[-sum]++;
                else
                    b[sum]++;
            }
        for(i=-50; i<=50; i++)
            for(j=-50; j<=50; j++)
                for(int k=-50; k<=50; k++)
                {
                    if(i==0 || j==0 || k==0)
                        continue;
                    int sum = a3*i*i*i + a4*j*j*j + a5*k*k*k;
                    if(-12500000<=sum && sum<=12500000)
                    {
                        if(sum < 0)
                        {
                            if(b[-sum] != 0)
                                ans += b[-sum];
                        }
                        else
                        {
                            if(a[sum] != 0)
                                ans += a[sum];
                        }
                    }
                }
        printf("%d
    ", ans);
        return 0;
    }


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  • 原文地址:https://www.cnblogs.com/Genesis2018/p/9079862.html
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