FilesExpand file tree

 master

/

StackOfLinkedList.java

Copy path

Blame

More file actions

Blame

More file actions

Latest commit

 

History

History

History

135 lines (112 loc) · 2.64 KB

 master

/

StackOfLinkedList.java

Top

File metadata and controls

• Code
• Blame

135 lines (112 loc) · 2.64 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

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

package DataStructures.Stacks;

import java.util.NoSuchElementException;

/** @author Varun Upadhyay (https://github.com/varunu28) */

// An implementation of a Stack using a Linked List

class StackOfLinkedList {

public static void main(String[] args) {

LinkedListStack stack = new LinkedListStack();

stack.push(1);

stack.push(2);

stack.push(3);

stack.push(4);

stack.push(5);

System.out.println(stack);

System.out.println("Size of stack currently is: " + stack.getSize());

assert stack.pop() == 5;

assert stack.pop() == 4;

System.out.println("Top element of stack currently is: " + stack.peek());

}

}

// A node class

class Node {

public int data;

public Node next;

public Node(int data) {

this.data = data;

this.next = null;

}

}

/**

* A class which implements a stack using a linked list

*

* <p>Contains all the stack methods : push, pop, printStack, isEmpty

*/

class LinkedListStack {

/** Top of stack */

Node head;

/** Size of stack */

private int size;

/** Init properties */

public LinkedListStack() {

head = null;

size = 0;

}

/**

* Add element at top

*

* @param x to be added

* @return <tt>true</tt> if add successfully

*/

public boolean push(int x) {

Node newNode = new Node(x);

newNode.next = head;

head = newNode;

size++;

return true;

}

/**

* Pop element at top of stack

*

* @return element at top of stack

* @throws NoSuchElementException if stack is empty

*/

public int pop() {

if (size == 0) {

throw new NoSuchElementException("Empty stack. Nothing to pop");

}

Node destroy = head;

head = head.next;

int retValue = destroy.data;

destroy = null; // clear to let GC do it's work

size--;

return retValue;

}

/**

* Peek element at top of stack

*

* @return element at top of stack

* @throws NoSuchElementException if stack is empty

*/

public int peek() {

if (size == 0) {

throw new NoSuchElementException("Empty stack. Nothing to pop");

}

return head.data;

}

@Override

public String toString() {

Node cur = head;

StringBuilder builder = new StringBuilder();

while (cur != null) {

builder.append(cur.data).append("->");

cur = cur.next;

}

return builder.replace(builder.length() - 2, builder.length(), "").toString();

}

/**

* Check if stack is empty

*

* @return <tt>true</tt> if stack is empty, otherwise <tt>false</tt>

*/

public boolean isEmpty() {

return size == 0;

}

/**

* Return size of stack

*

* @return size of stack

*/

public int getSize() {

return size;

}

}