codeforces 69A（Young Physicist） Java

水题，提神专用！！！

import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStreamWriter;import java.io.PrintWriter;import java.io.StreamTokenizer;/** * 题意：输入 n 行，每行三个数。每列的数相加都等于零，就输出"YES"，否则输出"NO" */public class Main {    public static void main(String[] args) throws IOException {        StreamTokenizer in = new StreamTokenizer(new BufferedReader(                new InputStreamReader(System.in)));        PrintWriter out = new PrintWriter(new BufferedWriter(                new OutputStreamWriter(System.out)));        int lineNum; // 行数        int sumA;        int sumB;        int sumC;        while (in.nextToken() != StreamTokenizer.TT_EOF) {            lineNum = (int) in.nval;            sumA = 0;            sumB = 0;            sumC = 0;            while (lineNum-- != 0) {                in.nextToken();                sumA += in.nval;                in.nextToken();                sumB += in.nval;                in.nextToken();                sumC += in.nval;            }            out.println(sumA == 0 && sumB == 0 && sumC == 0 ? "YES" : "NO");        }        out.flush();    }}