RUPC2016 Day1 A 秤 / Steelyard

問題

http://judge.u-aizu.ac.jp/onlinejudge/cdescription.jsp?cid=RitsCamp16Day1&pid=A

考察

吊らされたおもりと対称的におもりを吊っていく。
具体的にはに同じ重さのおもりを吊っていく。

ソースコード

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.NoSuchElementException;
 
public class Main {
    int L,N;
    int[] x,w;
    ArrayList<Integer>[] list;
    @SuppressWarnings("unchecked")
    public void solve() {
        L = nextInt();
        N = nextInt();
        x = new int[N];
        w = new int[N];
 
        list = new ArrayList[2 * L + 1];
        for(int i = 0;i < 2 * L + 1;i++){
            list[i] = new ArrayList<Integer>();
        }
        for(int i = 0;i < N;i++){
            x[i] = nextInt();
            w[i] = nextInt();
            list[-x[i] + L].add(w[i]);
        }
        out.println(N);
        for(int i = 0;i < 2 * L + 1;i++){
            for(int weight : list[i]){
                out.println((i-L) + " " + weight);
            }
        }
 
 
    }
    public static void main(String[] args) {
        out.flush();
        new Main().solve();
        out.close();
    }
 
    /* Input */
    private static final InputStream in = System.in;
    private static final PrintWriter out = new PrintWriter(System.out);
    private final byte[] buffer = new byte[2048];
    private int p = 0;
    private int buflen = 0;
 
    private boolean hasNextByte() {
        if (p < buflen)
            return true;
        p = 0;
        try {
            buflen = in.read(buffer);
        } catch (IOException e) {
            e.printStackTrace();
        }
        if (buflen <= 0)
            return false;
        return true;
    }
 
    public boolean hasNext() {
        while (hasNextByte() && !isPrint(buffer[p])) {
            p++;
        }
        return hasNextByte();
    }
 
    private boolean isPrint(int ch) {
        if (ch >= '!' && ch <= '~')
            return true;
        return false;
    }
 
    private int nextByte() {
        if (!hasNextByte())
            return -1;
        return buffer[p++];
    }
 
    public String next() {
        if (!hasNext())
            throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = -1;
        while (isPrint((b = nextByte()))) {
            sb.appendCodePoint(b);
        }
        return sb.toString();
    }
 
    public int nextInt() {
        return Integer.parseInt(next());
    }
 
    public long nextLong() {
        return Long.parseLong(next());
    }
 
    public double nextDouble() {
        return Double.parseDouble(next());
    }
}