HDU 3835 R(N)

R(N)

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 2761    Accepted Submission(s): 1420

Problem Description

We know that some positive integer x can be expressed as x=A^2+B^2(A,B are integers). Take x=10 for example,
10=(-3)^2+1^2.
We define R(N) (N is positive) to be the total number of variable presentation of N. So R(1)=4, which consists of 1=1^2+0^2, 1=(-1)^2+0^2, 1=0^2+1^2, 1=0^2+(-1)^2.Given N, you are to calculate R(N).

 

 

Input

No more than 100 test cases. Each case contains only one integer N(N<=10^9).

 

 

Output

For each N, print R(N) in one line.

 

 

Sample Input

2 6 10 25 65

 

 

Sample Output

4 0 8 12 16

Hint

For the fourth test case, (A,B) can be (0,5), (0,-5), (5,0), (-5,0), (3,4), (3,-4), (-3,4), (-3,-4), (4,3) , (4,-3), (-4,3), (-4,-3)

 

 

Source

2011 Multi-University Training Contest 1 - Host by HNU

 

 

Recommend

xubiao

暴力题，注意不要超时就行了，注意sqrt的数一定得是int类型的。

include <iostream>
#include <math.h>
#include <stdio.h>
using namespace std;
int main()
{
    int n;
    while(scanf("%d",&n)!=EOF)
    {
        if(n==0)
        {
            cout<<1<<endl;
            continue;
        }
        int c=sqrt(n/2);
        int ans=0;
        int i,j;
        for(i=0;i<=c;i++)
        {
            j=sqrt(n-i*i);
            if(i*i+j*j==n)
            {
                if(i==0||j==0||i==j)
                ans=ans+4;
                else
                ans=ans+8;
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}