[Function add]

1.Sequential symbol table.

Author: Seanforfun

Diff for: Algorithm(4th_Edition)/.classpath

@@ -2,5 +2,6 @@
 <classpath>
 	<classpathentry kind="src" path="src"/>
 	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/jre"/>
+	<classpathentry kind="lib" path="lib/algs4.jar"/>
 	<classpathentry kind="output" path="bin"/>
 </classpath>

Diff for: Algorithm(4th_Edition)/algorithm_note.txt

@@ -719,8 +719,57 @@
 			}						
 		}
 
+-------------------------------------------------------------------------------------------------------------------------
+---------------------------------------Chapter Three---------------------------------------------------------------------
+-------------------------------------------------------------------------------------------------------------------------			
+1. 符号表Symbol Table:
+	符号表的主要目的就是将一个键和一个值联系起来。
+	->重复的键：
+		1.每个键都对应一个值。
+		2.存入的键值对和已有的键起冲突时会覆盖旧的值。
+	->空键：
+		1.键不能为空。
+	->空值：
+		1.值不能为空。
+		2.可以通过get()方法返回值是不是null,来判断值是不是已经被删除。
+		3.put()空值用于删除。
 
+2. 通过链表实现的符号表：
+	实现：ca.mcmaster.chapter.three.SequentialSearchST<K, V>
+	这种符号表是无序的，属于随机命中。
+	public class SequentialSearchST<K, V> {
+		private class Node{
+			K k;
+			V v;
+			Node next;
+			public Node(K k, V v, Node next){
+				this.k = k;
+				this.v = v;
+				this.next = next;
+			}
+		}
+		private Node first;
+		public V get(K k){
+			Node current = first;
+			while(current != null){
+				if(current.k.equals(k))	return current.v;
+				current = current.next;
+			}
+			return null;
+		}
 
+		public void put(K k, V v){
+			Node current = first;
+			while(current != null){
+				if(current.k.equals(k)){
+					current.v = v;
+					return;
+				}
+				current = current.next;
+			}
+			first = new Node(k, v, first);
+		}				
+	}
 
 
 

Diff for: Algorithm(4th_Edition)/src/ca/mcmaster/chapter/three/SequentialSearchST.java

@@ -0,0 +1,50 @@
+package ca.mcmaster.chapter.three;
+
+public class SequentialSearchST<K, V> {
+	private class Node{
+		K k;
+		V v;
+		Node next;
+		public Node(K k, V v, Node next){
+			this.k = k;
+			this.v = v;
+			this.next = next;
+		}
+	}
+	private Node first;
+	public V get(K k){
+		Node current = first;
+		while(current != null){
+			if(current.k.equals(k))	return current.v;
+			current = current.next;
+		}
+		return null;
+	}
+	
+	public void put(K k, V v){
+		Node current = first;
+		while(current != null){
+			if(current.k.equals(k)){
+				current.v = v;
+				return;
+			}
+			current = current.next;
+		}
+		first = new Node(k, v, first);
+	}
+	
+	public static void main(String[] args) {
+		SequentialSearchST<String, String> table = new SequentialSearchST<>();
+		table.put("a", "aaaa");
+		table.put("b", "bbbb");
+		table.put("c", "cccc");
+		table.put("d", "dddd");
+		System.out.println(table.get("a"));
+		System.out.println(table.get("b"));
+		System.out.println(table.get("c"));
+		System.out.println(table.get("d"));
+		table.put("a", "1111");
+		System.out.println(table.get("a"));
+		System.out.println(table.get("p"));
+	}
+}