結果

問題 No.947 ABC包囲網
ユーザー uwiuwi
提出日時 2019-12-10 00:53:28
言語 Java
(openjdk 23)
結果
AC  
実行時間 172 ms / 2,000 ms
コード長 5,433 bytes
コンパイル時間 4,199 ms
コンパイル使用メモリ 84,612 KB
実行使用メモリ 43,944 KB
最終ジャッジ日時 2024-06-23 10:58:29
合計ジャッジ時間 11,009 ms
ジャッジサーバーID
（参考情報） 		judge2 / judge5
このコードへのチャレンジ
（要ログイン）
ファイルパターン 結果
other AC * 60
権限があれば一括ダウンロードができます

ソースコード

diff # 

package adv2019;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Comparator;
import java.util.InputMismatchException;

public class D10 {
	InputStream is;
	PrintWriter out;
	String INPUT = ""; 
	
	void solve()
	{
		int n = ni();
		int[][] co = new int[n][];
		for(int i = 0;i < n;i++) {
			co[i] = na(2);
		}
		int p = 0;
		for(int i = 0;i < n;i++) {
			if(co[i][0] == 0 && co[i][1] == 0)continue;
			co[p++] = co[i];
		}
		co = Arrays.copyOf(co, p);
		n = p;
		
		Arrays.sort(co, compArgi);
		
		long ans = (long)n*(n-1)*(n-2)/6;
		{
			int k = 0;
			for(int i = 0;i < n;i++) {
				while(k-i < n && (isACB(new int[] {0, 0}, co[k%n], co[i]) || ccw(new int[] {0, 0}, co[i], co[k%n]) == -1)) {
	//				tr(co[i], co[k], isACB(co[i], new int[] {0, 0}, co[k]));
					k++;
				}
				ans -= (k-i-1)*(k-i-2)/2;
			}
		}
		for(int i = 0;i < n;) {
			int same = 1, diff = 0;
			if(co[i][1] < 0 || co[i][1] == 0 && co[i][0] < 0)break;
			for(int j = i+1;j < n;j++) {
				if(ccw(new int[] {0, 0}, co[i], co[j]) == 0) {
					if(isACB(new int[] {0, 0}, co[j], co[i])) {
						same++;
					}else {
						diff++;
					}
				}
			}
			// (n-2)+(n-3)+..+(n-diff-1)
			// (n-3)+(n-4)+..+(n-diff-2)
			// (n-same-1)+...
			
			long s = 0;
			for(int k = 2;k <= diff+1;k++) {
				s += n-k;
			}
			for(int k = 2;k <= same+1;k++) {
				ans -= s;
				s -= diff;
			}
			
			i += same;
		}
		out.println(ans);
	}
	
	public static boolean isACB(long ax, long ay, long bx, long by, long cx, long cy)
	{
		return (cx-ax)*(by-ay)-(cy-ay)*(bx-ax)==0 && (cx-ax)*(cx-bx)+(cy-ay)*(cy-by) <= 0;
	}
	
	public static boolean isACB(long[] a, long[] b, long[] c) { return isACB(a[0], a[1], b[0], b[1], c[0], c[1]); }
	public static boolean isACB(int[] a, int[] b, int[] c) { return isACB(a[0], a[1], b[0], b[1], c[0], c[1]); }


	
	public static int ccw(long ax, long ay, long bx, long by, long tx, long ty){ return Long.signum((tx-ax)*(by-ay)-(bx-ax)*(ty-ay)); }
	public static int ccw(long[] a, long[] b, long[] t){ return Long.signum((t[0]-a[0])*(b[1]-a[1])-(b[0]-a[0])*(t[1]-a[1])); }
	public static int ccw(int[] a, int[] b, int[] t){ return Long.signum((long)(t[0]-a[0])*(b[1]-a[1])-(long)(b[0]-a[0])*(t[1]-a[1])); }

	
	public static Comparator<int[]> compArgi = new Comparator<int[]>(){
		public int compare(int[] a, int[] b)
		{
			long ax = a[0], ay = a[1];
			long bx = b[0], by = b[1];
			int za = ay > 0 || ay == 0 && ax > 0 ? 0 : 1;
			int zb = by > 0 || by == 0 && bx > 0 ? 0 : 1;
			if(za != zb)return za - zb;
			if(ay*bx-ax*by != 0)return Long.signum(ay*bx-ax*by);
			return Long.signum((ax*ax+ay*ay)-(bx*bx+by*by));
		}
	};

	
	void run() throws Exception
	{
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		long s = System.currentTimeMillis();
		solve();
		out.flush();
		if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//		Thread t = new Thread(null, null, "~", Runtime.getRuntime().maxMemory()){
//			@Override
//			public void run() {
//				long s = System.currentTimeMillis();
//				solve();
//				out.flush();
//				if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//			}
//		};
//		t.start();
//		t.join();
	}
	
	public static void main(String[] args) throws Exception { new D10().run(); }
	
	private byte[] inbuf = new byte[1024];
	public int lenbuf = 0, ptrbuf = 0;
	
	private int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private double nd() { return Double.parseDouble(ns()); }
	private char nc() { return (char)skip(); }
	
	private String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private long[] nal(int n)
	{
		long[] a = new long[n];
		for(int i = 0;i < n;i++)a[i] = nl();
		return a;
	}
	
	private char[][] nm(int n, int m) {
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private int[][] nmi(int n, int m) {
		int[][] map = new int[n][];
		for(int i = 0;i < n;i++)map[i] = na(m);
		return map;
	}
	
	private int ni() { return (int)nl(); }
	
	private long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); }
}
0