DataStructuresInPython/linkedlist.py at main · ZohaibRamzan/DataStructuresInPython · GitHub

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
# The Code is written to revise Data Structures for python Language
# Below code is for LinkedList Data Structure
# Big(O) for insert at start and end is O(1)
# Advantage of linkedlist over Array is it expends(add new element) as the requirement increases
class Node:
    def __init__(self, data=None,next=None):
        self.data=data
        self.next=next
class linkedlist:
    def __init__(self):
        self.head= None

 # insert element to linkedlist
    def add_element(self, data):
        node=Node(data,self.head)
        self.head=node
        return
 # remove the element as per index value
    def remove_at_index(self,index):
        leng=self.get_length()
        #print(leng)
        itr=self.head
        for i in range(leng):
            if i==index-1:
                itr.next=itr.next.next
                break
            itr=itr.next

# reverse linkedlist
        def reverse_ll(self):
        itr=self.head
        arr=[]
        while itr:
            arr.append(itr.data)
            itr=itr.next
        b = linkedlist()
        for element in arr:
            print(element)
            b.insert_element((element))
        b.print_ll()

# list to linkedlist
    def List_to_ll(self, arr):
        for ele in arr:
            self.insert_at_end(ele)


# insert element at end of linkedlist
    def insert_at_end(self,data):
        if self.head==None:   # means empty object
            self.head=Node(data,None)
            return
        itr=self.head
        while itr.next:
            itr=itr.next
        itr.next=Node(data,None)


    def print_ll(self):
        if self.head==None:
            print('Linked list is empty')
            return
        itr=self.head
        linked_list=''
        while itr:
            linked_list+=str(itr.data)+ '--->'
            itr=itr.next
        print(linked_list)

# get length of linkedlist
    def get_length(self):
        count=0
        itr=self.head
        while itr:
            count+=1
            itr=itr.next
        return count

    def insert_at(self,index,elem):
        if index==0:
            node=Node(elem,self.head)
            self.head=node
        itr= self.head
        leng=self.get_length()
        for i in range(leng):
            if i == index - 1:
                itr.next = Node(elem,itr.next)
            itr = itr.next
# Exercise Solutions
    def remove_by_value(self, value):
        itr=self.head
        index=0
        while itr:
            if itr.data==value:
                self.remove_at_index(index)
                break
            index+=1
            itr=itr.next

    def insert_after_value(self,data, data_after):
        itr=self.head
        while itr:
            if itr.data==data:
                itr.next=Node(data_after,itr.next)
                break
            itr=itr.next


if __name__=="__main__":
    a=linkedlist()
    a.add_element(12)
    a.add_element(34)
    a.print_ll()
    a.insert_at_end(100)
    a.print_ll()
    numbers=[12,23,54,65]
    b=linkedlist()
    b.List_to_ll(numbers)
    b.print_ll()
    length=b.get_length()
    print('length',length)
    b.remove_at_index(1)
    b.print_ll()
    b.insert_at(1,344)
    b.print_ll()


    ### Exercise
    b.remove_by_value(54)
    b.print_ll()
    fruits=['banana','Mango','grapes','orange']
    c = linkedlist()
    c.List_to_ll(fruits)
    c.insert_after_value('Mango', 'Apple')
    c.print_ll()