Poj Solution 2785

http://poj.org/problem?id=2785

//* @author: 82638882@163.com
import java.io.*;
import java.util.*;
public class Main
{
 public static void main(String[] args) throws IOException
 {
    InputStreamReader is=new InputStreamReader(System.in);
    BufferedReader in=new BufferedReader(is);
    String s=in.readLine();
    int a=Integer.parseInt(s);
    int[] t1=new int[a];
    int[] t2=new int[a];
    int[] t3=new int[a];
    int[] t4=new int[a];
    int[] t5=new int[a*a];
    int[] t6=new int[a*a];
    int abl=0,cdl=0;
    String[] ss;
    for(int i=0;i< a;i++)
    {
         ss=in.readLine().split(" ");
      t1[i]=Integer.parseInt(ss[0]);
      t2[i]=Integer.parseInt(ss[1]);
      t3[i]=Integer.parseInt(ss[2]);
      t4[i]=Integer.parseInt(ss[3]);
    }
    for(int i=0;i< a;i++)
      for(int j=0;j< a;j++)
      {
       t5[abl++]=t1[i]+t2[j];
       t6[cdl++]=t3[i]+t4[j];
      }
    Arrays.sort(t5);
    Arrays.sort(t6);
    int l1=0,l2=cdl-1,ans=0,k,m;
    while(l1< abl&&l2>-1)
    {
      if(t5[l1]+t6[l2]==0){
        k=0;
        m=0;
        for(int i=l1;i< abl;i++)
             if(t5[l1]!=t5[i]) break;
          else k++;
        l1+=k;
        for(int i=l2;i>-1;i--)
          if(t6[l2]!=t6[i]) break;
          else m++;
        l2-=m;
        ans+=k*m;
      }
      else if(t5[l1]+t6[l2]>0) l2--;
      else l1++;
      }
      System.out.println(ans);
  }
}