符号表

public class ST<Key, Value>
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	ST()
	void put(Key key, Value value)
	Value get(Key key)
	void delete(Key key)
	boolean contains(Key key)
	boolean isEmpty()
	int size()
	Iterable<Key> keys()

	public final class Date implements Comparable<Date> {
		private final int month;
	   	private final int day;
   		private final int year;
   		...
   		
   		public boolean equals(Object y) {
   			//check for null
   			if(y == null) retrun false;
   			
   			//check for true equals
   			if(y == this) return true;
   			
   			//objects must be in the same class
   			if(y.getClass() != this.getClass()) return false;
   			
   			//
   			Date that = (Date) y;
   			if (this.day   != that.day  ) return false;
      		if (this.month != that.month) return false;
      		if (this.year  != that.year ) return false;   			return true;
   		}
	}

	public Value get(Key key) {
		if(isEmpty()) return null;
		int i = rank(key);
		if(i < N && keys[i].compareTo(key) == 0) return vals[i];
		else return null;
	}
	//number of keys < key
	private int rank(Key key) {
		int lo = 0, hi = N - 1;
		while(lo <= hi) {
			int mid = lo + (hi - lo) / 2;
			int cmp = key.compareTo(keys[mid]);
			if(cmp < 0) hi = mid - 1;
			else if (cmp > 0) lo = mid + 1;
			else return mid;
		}
		return lo;
	}

public class ST<Key extends Comparable<Key>, Value>
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		ST()
				
		void put(Key key, Value val)
				
		Value get(Key key)
				
		void delete(Key key)
				
		boolean contains(Key key)
				
		boolean isEmpty()
				
		int size()
				
		Key min()
				
		Key max()
				
		Key floor(Key key)
				
		Key ceiling(Key key)
				
		int rank(Key key)
				
		Key select(int k)			
	
		void deleteMin()
				
		void deleteMax()
				
		int size(Key lo, Key hi)
				
		Iterable<Key>	 keys(Key lo, Key hi)
				
		Iterable<Key> keys()