-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathExpression-Tree.java
More file actions
235 lines (206 loc) · 5.2 KB
/
Expression-Tree.java
File metadata and controls
235 lines (206 loc) · 5.2 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
import java.util.Scanner;
/** Class ExpressionTree **/
class ExpressionTree
{
/** class TreeNode **/
class TreeNode
{
char data;
TreeNode left, right;
/** constructor **/
public TreeNode(char data)
{
this.data = data;
this.left = null;
this.right = null;
}
}
/** class StackNode **/
class StackNode
{
TreeNode treeNode;
StackNode next;
/** constructor **/
public StackNode(TreeNode treeNode)
{
this.treeNode = treeNode;
next = null;
}
}
private static StackNode top;
/** constructor **/
public ExpressionTree()
{
top = null;
}
/** function to clear tree **/
public void clear()
{
top = null;
}
/** function to push a node **/
private void push(TreeNode ptr)
{
if (top == null)
top = new StackNode(ptr);
else
{
StackNode nptr = new StackNode(ptr);
nptr.next = top;
top = nptr;
}
}
/** function to pop a node **/
private TreeNode pop()
{
if (top == null)
throw new RuntimeException("Underflow");
else
{
TreeNode ptr = top.treeNode;
top = top.next;
return ptr;
}
}
/** function to get top node **/
private TreeNode peek()
{
return top.treeNode;
}
/** function to insert character **/
private void insert(char val)
{
try
{
if (isDigit(val))
{
TreeNode nptr = new TreeNode(val);
push(nptr);
}
else if (isOperator(val))
{
TreeNode nptr = new TreeNode(val);
nptr.left = pop();
nptr.right = pop();
push(nptr);
}
}
catch (Exception e)
{
System.out.println("Invalid Expression");
}
}
/** function to check if digit **/
private boolean isDigit(char ch)
{
return ch >= '0' && ch <= '9';
}
/** function to check if operator **/
private boolean isOperator(char ch)
{
return ch == '+' || ch == '-' || ch == '*' || ch == '/';
}
/** function to convert character to digit **/
private int toDigit(char ch)
{
return ch - '0';
}
/** function to build tree from input */
public void buildTree(String eqn)
{
for (int i = eqn.length() - 1; i >= 0; i--)
insert(eqn.charAt(i));
}
/** function to evaluate tree */
public double evaluate()
{
return evaluate(peek());
}
/** function to evaluate tree */
public double evaluate(TreeNode ptr)
{
if (ptr.left == null && ptr.right == null)
return toDigit(ptr.data);
else
{
double result = 0.0;
double left = evaluate(ptr.left);
double right = evaluate(ptr.right);
char operator = ptr.data;
switch (operator)
{
case '+' : result = left + right; break;
case '-' : result = left - right; break;
case '*' : result = left * right; break;
case '/' : result = left / right; break;
default : result = left + right; break;
}
return result;
}
}
/** function to get postfix expression */
public void postfix()
{
postOrder(peek());
}
/** post order traversal */
private void postOrder(TreeNode ptr)
{
if (ptr != null)
{
postOrder(ptr.left);
postOrder(ptr.right);
System.out.print(ptr.data);
}
}
/** function to get infix expression */
public void infix()
{
inOrder(peek());
}
/** in order traversal */
private void inOrder(TreeNode ptr)
{
if (ptr != null)
{
inOrder(ptr.left);
System.out.print(ptr.data);
inOrder(ptr.right);
}
}
/** function to get prefix expression */
public void prefix()
{
preOrder(peek());
}
/** pre order traversal */
private void preOrder(TreeNode ptr)
{
if (ptr != null)
{
System.out.print(ptr.data);
preOrder(ptr.left);
preOrder(ptr.right);
}
}
}
/** class ExpressionTreeTest **/
public class ExpressionTreeTest
{
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
System.out.println("Expression Tree Test");
/** make object of ExpressionTree **/
ExpressionTree et = new ExpressionTree();
System.out.println("\nEnter equation in prefix form");
et.buildTree(scan.next());
System.out.print("\nPrefix : ");
et.prefix();
System.out.print("\n\nInfix : ");
et.infix();
System.out.print("\n\nPostfix : ");
et.postfix();
System.out.println("\n\nEvaluated Result : "+ et.evaluate());
}
}