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package algs35;
import stdlib.*;
import java.util.Iterator;
import java.util.SortedMap;
import java.util.TreeMap;
/* ***********************************************************************
 *  Compilation:  javac ST.java
 *  Execution:    java ST
 *
 *  Sorted symbol table implementation using a java.util.TreeMap.
 *  Does not allow duplicates.
 *
 *  % java ST
 *
 *************************************************************************/

/**
 *  This class represents an ordered symbol table. It assumes that
 *  the keys are <tt>Comparable</tt>.
 *  It supports the usual <em>put</em>, <em>get</em>, <em>contains</em>,
 *  and <em>remove</em> methods.
 *  It also provides ordered methods for finding the <em>minimum</em>,
 *  <em>maximum</em>, <em>floor</em>, and <em>ceiling</em>.
 *  <p>
 *  The class implements the <em>associative array</em> abstraction: when associating
 *  a value with a key that is already in the table, the convention is to replace
 *  the old value with the new value.
 *  The class also uses the convention that values cannot be null. Setting the
 *  value associated with a key to null is equivalent to removing the key.
 *  <p>
 *  This class implements the Iterable interface for compatiblity with
 *  the version from <em>Introduction to Programming in Java: An Interdisciplinary
 *  Approach</em>.
 *  <p>
 *  This implementation uses a balanced binary search tree.
 *  The <em>put</em>, <em>contains</em>, <em>remove</em>, <em>minimum</em>,
 *  <em>maximum</em>, <em>ceiling</em>, and <em>floor</em> methods take
 *  logarithmic time.
 *  <p>
 *  For additional documentation, see <a href="http://algs4.cs.princeton.edu/35applications">Section 4.5</a> of
 *  <i>Algorithms, 4th Edition</i> by Robert Sedgewick and Kevin Wayne.
 */
public class ST<K extends Comparable<? super K>, V> implements Iterable<K> {

  private final TreeMap<K, V> st;

  /**
   * Create an empty symbol table.
   */
  public ST() {
    st = new TreeMap<>();
  }

  /**
   * Put key-value pair into the symbol table. Remove key from table if
   * value is null.
   */
  public void put(K key, V val) {
    if (val == null) st.remove(key);
    else             st.put(key, val);
  }

  /**
   * Return the value paired with given key; null if key is not in table.
   */
  public V get(K key) {
    return st.get(key);
  }

  /**
   * Delete the key (and paired value) from table.
   * Return the value paired with given key; null if key is not in table.
   */
  public V delete(K key) {
    return st.remove(key);
  }

  /**
   * Is the key in the table?
   */
  public boolean contains(K key) {
    return st.containsKey(key);
  }

  /**
   * How many keys are in the table?
   */
  public int size() {
    return st.size();
  }

  /**
   * Return an <tt>Iterable</tt> for the keys in the table.
   * To iterate over all of the keys in the symbol table <tt>st</tt>, use the
   * foreach notation: <tt>for (K key : st.keys())</tt>.
   */
  public Iterable<K> keys() {
    return st.keySet();
  }

  /**
   * Return an <tt>Iterator</tt> for the keys in the table.
   * To iterate over all of the keys in the symbol table <tt>st</tt>, use the
   * foreach notation: <tt>for (K key : st)</tt>.
   * This method is for backward compatibility with the version from <em>Introduction
   * to Programming in Java: An Interdisciplinary Approach.</em>
   */
  public Iterator<K> iterator() {
    return st.keySet().iterator();
  }

  /**
   * Return the smallest key in the table.
   */
  public K min() {
    return st.firstKey();
  }

  /**
   * Return the largest key in the table.
   */
  public K max() {
    return st.lastKey();
  }


  /**
   * Return the smallest key in the table >= k.
   */
  public K ceil(K k) {
    SortedMap<K, V> tail = st.tailMap(k);
    if (tail.isEmpty()) return null;
    else return tail.firstKey();
  }

  /**
   * Return the largest key in the table <= k.
   */
  public K floor(K k) {
    if (st.containsKey(k)) return k;

    // does not include key if present (!)
    SortedMap<K, V> head = st.headMap(k);
    if (head.isEmpty()) return null;
    else return head.lastKey();
  }

  /* *********************************************************************
   * Test routine.
   **********************************************************************/
  public static void main(String[] args) {
    ST<String, Integer> st = new ST<>();
    for (int i = 0; !StdIn.isEmpty(); i++) {
      String key = StdIn.readString();
      st.put(key, i);
    }
    for (String s : st.keys())
      StdOut.println(s + " " + st.get(s));
  }

}