HDU 3835 R(N)

R(N)

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 1460    Accepted Submission(s): 763

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

 

#include<stdio.h>
#include<math.h>
 
int main()
{
    int k,i,j,n,ans;
    while(~scanf("%d",&n))
    {
        if(!n)
        {
            printf("1\n");
            continue;
        }
        ans=0;
        k=(int)sqrt(n/2.0);
        for(i=0;i<=k;++i)
        {
            j=(int)sqrt(n-i*i);
            if(i*i+j*j==n)
            {
                if(i==j||i==0||j==0)  //其中有一个为0或者x==y时候只有四种情况
                    ans+=4;
                else
                    ans+=8;    //x与y不为0且不相等的时候有8种情况
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}