1、按 salepoint 排序， 再做统计。 
2、做顺序统计的过程中， 不要使用 print ， 而是使用 StringBuilder 把输出的内容装着。 
3、在最后把 BtringBuilder 对象包含的内容打出来。 

由于此题需要打屏输出大量数据， 每次调用 print 会消耗很多的时间。 

注： Collection.sort 方法调用的是归并排序来的， 所以排序的效率算稳定。 


import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.List;
import java.util.StringTokenizer;

public class Main {
	/**
	 * @param args
	 * @throws IOException 
	 */
	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
//				new BufferedReader(new FileReader(new File("C:\\Users\\jackchongs\\workspace\\POJ\\src\\test.txt")));
		int N = Integer.valueOf(br.readLine());
		
		HashSet<Integer> items  = 
				 new HashSet<Integer>();

		HashSet<Integer> salePoints  = 
				 new HashSet<Integer>();

		List<Triplets> list 
		    = new ArrayList<Triplets>();
		
		long begin = System.currentTimeMillis();
		for (int i = 0; i < N; i++) { 
			String str = br.readLine();
			StringTokenizer stoken = new StringTokenizer(str, " ");
			int qi = Integer.valueOf(stoken.nextToken());
			int si = Integer.valueOf(stoken.nextToken());
			int vi = Integer.valueOf(stoken.nextToken());
			
//			String tmp [] = str.split(" ");
//			
//			int qi = Integer.valueOf(tmp[0]);
//			int si = Integer.valueOf(tmp[1]);
//			int vi = Integer.valueOf(tmp[2]);
			
			if( ! items.contains(qi))  items.add(qi);
			if( ! salePoints.contains(si))  salePoints.add(si);
			list.add(new Triplets(qi, si, vi));
		}
		Collections.sort(list, new MyComparator());
		List<Integer> listItems = new ArrayList<Integer>(items);
		List<Integer> listSalePoints = new ArrayList<Integer>(salePoints);
		
		Collections.sort(listItems);
		Collections.sort(listSalePoints);
		
//		System.out.println(list);
//		System.out.println(listItems);
//		System.out.println(listSalePoints);
		
		System.out.print("-1");
		for (Integer curItem : listItems ) {
			System.out.print(" " + curItem );
		}
		System.out.println();
		
		Triplets tmp = null;
		tmp = list.get(0);
		int k = 1;
		StringBuffer strBuff = new StringBuffer();
		for (int i = 0; i < listSalePoints.size(); i++) {
//			System.out.print( listSalePoints.get(i)+ " ");
			strBuff.append(listSalePoints.get(i));
			strBuff.append(" ");
			for (int j = 0; j < listItems.size(); j++) {
				if( tmp.qi !=  listItems.get(j)
						|| tmp.si !=listSalePoints.get(i) ) 
				{
//					System.out.print("0");
					strBuff.append("0");
					if( j != listItems.size() -1 ) 
					{
//						System.out.print(" ");
						strBuff.append(" ");
					}
				}
				else 
				{
					int sum = tmp.vi;
					while( k < list.size()&& tmp.qi == list.get(k).qi
							&& tmp.si == list.get(k).si 
							)
					{
						sum += list.get(k).vi;
						k++;
					}

					if( k < list.size()) 
					{
						tmp = list.get(k);
						k++;
					}

//					System.out.print(sum);
					strBuff.append(sum);
					if( j != listItems.size() -1 ) 
					{
//						System.out.print(" ");
						strBuff.append(" ");
					}
				}
			}
//			System.out.println();
			strBuff.append("\n");
		}
		System.out.print(strBuff.toString());
		long end = System.currentTimeMillis();
//		System.out.println( end - begin );
		br.close();
	}
}

class Triplets
{
	int qi = 0;
	int si = 0;
	int vi = 0; 
	public Triplets( int in_qi , 
			int in_si, int in_vi )
	{
		qi = in_qi;
		si = in_si; 
		vi = in_vi;
	}
	
	public String toString() 
	{
		return "("+ qi 
				+","
				+ si 
				+","
				+ vi + ")";
	}
}

class MyComparator implements Comparator<Triplets>
{
	public int compare( Triplets a, Triplets b ) 
	{
		if( a.si > b.si ) return 1; 
		else if( a.si == b.si )
		{
			if(a.qi > b.qi 	) return 1;
			else  return -1;
		}
		else 
		{
			return -1;
		}
	}
}