BINARY SEARCH TREES - Introduction to Java Programming: Comprehensive Version - page 958

80 public Tree(Tree t1, Tree t2) {
81 root = new Node();
82 root.left = t1.root;
83 root.right = t2.root;
84 root.weight = t1.root.weight + t2.root.weight;
85 }
86
87 /** Create a tree containing a leaf node */
88 public Tree( int weight, char element) {
89 root = new Node(weight, element);
90 }
91
92 @Override /** Compare trees based on their weights */
93

public int compareTo(Tree t) {

94 if (root.weight < t.root.weight) // Purposely reverse the order

95 return 1 ;

96 else if (root.weight == t.root.weight)

97 return 0 ;

98 else

99 return -1 ;

100 }
101
102 public class Node {
103 char element; // Stores the character for a leaf node
104 int weight; // weight of the subtree rooted at this node
105 Node left; // Reference to the left subtree
106 Node right; // Reference to the right subtree
107 String code = "" ; // The code of this node from the root
108
109 /** Create an empty node */
110 public Node() {
111 }
112
113

tree node

/** Create a node with the specified weight and character */

114 public Node( int weight, char element) {

115 this .weight = weight;

116 this .element = element;

117 }
118 }
119 }
120 }

Enter text: Welcome
ASCII Code Character Frequency Code
87 W 1 110
99 c 1 111
101 e 2 10
108 l 1 011
109 m 1 010
111 o 1 00

The program prompts the user to enter a text string (lines 5-7) and counts the frequency
of the characters in the text (line 9). The getCharacterFrequency method (lines
66-73) creates an array counts to count the occurrences of each of the 256 ASCII char-
acters in the text. If a character appears in the text, its corresponding count is increased
by 1 (line 70).

getCharacterFrequency