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AtCoder Regular Contest 033 C - データ構造

AtCoder 競技プログラミング

解法

Treap を実装した。

コード

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.NoSuchElementException;
import java.util.Random;

/*
                   _ooOoo_
                  o8888888o
                  88" . "88
                  (| -_- |)
                  O\  =  /O
               ____/`---'\____
             .'  \\|     |//  `.
            /  \\|||  :  |||//  \
           /  _||||| -:- |||||-  \
           |   | \\\  -  /// |   |
           | \_|  ''\---/''  |   |
           \  .-\__  `-`  ___/-. /
         ___`. .'  /--.--\  `. . __
      ."" '<  `.___\_<|>_/___.'  >'"".
     | | :  `- \`.;`\ _ /`;.`/ - ` : | |
     \  \ `-.   \_ __\ /__ _/   .-` /  /
======`-.____`-.___\_____/___.-`____.-'======
                   `=---='
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
            pass System Test!
*/

public class Main {
  private static class Task {
    void solve(FastScanner in, PrintWriter out) throws Exception {
      Treap treap = new Treap();
      int Q = in.nextInt();
      for (int i = 0; i < Q; i++) {
        int t = in.nextInt();
        int x = in.nextInt();

        if (t == 1) {
          treap.insert(x);
        } else {
          long key = treap.rank(x - 1);
          out.println(key);
          treap.erase(key);
        }

      }
    }

    class Treap {
      Random random = new Random();

      class Node {
        Node left, right;
        long key;
        int priority;
        int count;

        Node(long key) {
          this.key = key;
          priority = random.nextInt();
          left = null;
          right = null;
          count = 1;
        }
      }

      Node root = null;

      int count(Node n) {
        return n == null ? 0 : n.count;
      }

      void update(Node c) {
        c.count = 1 + count(c.left) + count(c.right);
      }

      Node leftRotate(Node c) {
        Node r = c.right;
        c.right = r.left;
        r.left = c;
        update(c);
        return r;
      }

      Node rightRotate(Node c) {
        Node l = c.left;
        c.left = l.right;
        l.right = c;
        update(c);
        return l;
      }

      Node insert(Node c, long key) {
        if (c == null) return new Node(key);
        if (c.key < key) {
          c.right = insert(c.right, key);
          if (c.right.priority < c.priority) c = leftRotate(c);
        } else {
          c.left = insert(c.left, key);
          if (c.left.priority < c.priority) c = rightRotate(c);
        }
        update(c);
        return c;
      }

      Node getMinNode(Node c) {
        while (c.left != null) c = c.left;
        return c;
      }

      Node erase(Node c, long key) {
        if (key == c.key) {
          if (c.left == null) return c.right;
          if (c.right == null) return c.left;

          Node minNode = getMinNode(c.right);
          c.key = minNode.key;
          c.right = erase(c.right, minNode.key);
        } else {
          if (c.key < key) c.right = erase(c.right, key);
          else c.left = erase(c.left, key);
        }
        update(c);
        return c;
      }

      void insert(long key) {
        if (contains(key)) return;
        root = insert(root, key);
      }

      void erase(long key) {
        root = erase(root, key);
      }

      int size() {
        return count(root);
      }

      boolean contains(long key) {
        return find(root, key) >= 0;
      }

      int find(long key) {
        return find(root, key);
      }

      int find(Node c, long key) {
        if (c == null) return -1;
        if (c.key == key) return count(c.left);
        if (key < c.key) return find(c.left, key);
        int pos = find(c.right, key);
        if (pos < 0) return pos;
        return count(c.left) + 1 + pos;
      }

      Node rank(Node c, int rank) {
        while (c != null) {
          int leftCount = count(c.left);
          if (leftCount == rank) return c;
          if (leftCount < rank) {
            rank -= leftCount + 1;
            c = c.right;
          } else {
            c = c.left;
          }
        }
        return c;
      }

      long rank(int rank) {
        return rank(root, rank).key;
      }

    }

  }

  /**
   * ここから下はテンプレートです。
   */
  public static void main(String[] args) throws Exception {
    OutputStream outputStream = System.out;
    FastScanner in = new FastScanner();
    PrintWriter out = new PrintWriter(outputStream);
    Task solver = new Task();
    solver.solve(in, out);
    out.close();
  }
  private static class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int bufferLength = 0;

    private boolean hasNextByte() {
      if (ptr < bufferLength) {
        return true;
      } else {
        ptr = 0;
        try {
          bufferLength = in.read(buffer);
        } catch (IOException e) {
          e.printStackTrace();
        }
        if (bufferLength <= 0) {
          return false;
        }
      }
      return true;
    }

    private int readByte() {
      if (hasNextByte()) return buffer[ptr++];
      else return -1;
    }

    private static boolean isPrintableChar(int c) {
      return 33 <= c && c <= 126;
    }

    private void skipUnprintable() {
      while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
    }

    boolean hasNext() {
      skipUnprintable();
      return hasNextByte();
    }

    public String next() {
      if (!hasNext()) throw new NoSuchElementException();
      StringBuilder sb = new StringBuilder();
      int b = readByte();
      while (isPrintableChar(b)) {
        sb.appendCodePoint(b);
        b = readByte();
      }
      return sb.toString();
    }

    long nextLong() {
      if (!hasNext()) throw new NoSuchElementException();
      long n = 0;
      boolean minus = false;
      int b = readByte();
      if (b == '-') {
        minus = true;
        b = readByte();
      }
      if (b < '0' || '9' < b) {
        throw new NumberFormatException();
      }
      while (true) {
        if ('0' <= b && b <= '9') {
          n *= 10;
          n += b - '0';
        } else if (b == -1 || !isPrintableChar(b)) {
          return minus ? -n : n;
        } else {
          throw new NumberFormatException();
        }
        b = readByte();
      }
    }

    double nextDouble() {
      return Double.parseDouble(next());
    }

    double[] nextDoubleArray(int n) {
      double[] array = new double[n];
      for (int i = 0; i < n; i++) {
        array[i] = nextDouble();
      }
      return array;
    }

    double[][] nextDoubleMap(int n, int m) {
      double[][] map = new double[n][];
      for (int i = 0; i < n; i++) {
        map[i] = nextDoubleArray(m);
      }
      return map;
    }

    public int nextInt() {
      return (int) nextLong();
    }

    public int[] nextIntArray(int n) {
      int[] array = new int[n];
      for (int i = 0; i < n; i++) array[i] = nextInt();
      return array;
    }

    public long[] nextLongArray(int n) {
      long[] array = new long[n];
      for (int i = 0; i < n; i++) array[i] = nextLong();
      return array;
    }

    public String[] nextStringArray(int n) {
      String[] array = new String[n];
      for (int i = 0; i < n; i++) array[i] = next();
      return array;
    }

    public char[][] nextCharMap(int n) {
      char[][] array = new char[n][];
      for (int i = 0; i < n; i++) array[i] = next().toCharArray();
      return array;
    }

    public int[][] nextIntMap(int n, int m) {
      int[][] map = new int[n][];
      for (int i = 0; i < n; i++) {
        map[i] = nextIntArray(m);
      }
      return map;
    }
  }
}