Submission #25772517

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Source Code Expand

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Collection;
import java.util.Set;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.TreeSet;
import java.util.stream.Stream;
import java.util.TreeMap;
import java.util.StringTokenizer;
import java.util.Map;
import java.io.BufferedReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        MyScanner in = new MyScanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        D solver = new D();
        solver.solve(1, in, out);
        out.close();
    }

    static class D {
        public void solve(int testNumber, MyScanner in, PrintWriter out) {
            int N = in.Int();
            TreeMap<Integer, Set<Integer>> map = new TreeMap<>();
            for (int n = 0; n < N; n++) {
                int x = in.Int();
                int y = in.Int();
                Set<Integer> set = map.getOrDefault(x, new TreeSet<>());
                set.add(y);
                map.put(x, set);
            }

            long ans = 0;
            var keys = map.keySet().toArray(new Integer[0]);
            for (int i = 0; i < keys.length; i++) {
                Set<Integer> set1 = map.get(keys[i]);
                for (int j = i + 1; j < keys.length; j++) {
                    Set<Integer> set2 = map.get(keys[j]);
                    long cnt = set1.stream().filter(set2::contains).count();
                    ans += cnt * (cnt - 1) / 2;
                }
            }
            out.println(ans);
        }

    }

    static class MyScanner {
        private BufferedReader in;
        private StringTokenizer st;

        public MyScanner(InputStream stream) {
            in = new BufferedReader(new InputStreamReader(stream));
        }

        public String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    String rl = in.readLine();
                    if (rl == null) {
                        return null;
                    }
                    st = new StringTokenizer(rl);
                } catch (IOException e) {
                    return null;
                }
            }
            return st.nextToken();
        }

        public int Int() {
            return Integer.parseInt(next());
        }

    }
}

Submission Info

Judge Result