leetcode_python_150/138_Copy_List_with_Random_Pointer.py at main · Ishazaka/leetcode_python_150 · GitHub

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#1st way
"""
# Definition for a Node.
class Node:
    def __init__(self, x: int, next: 'Node' = None, random: 'Node' = None):
        self.val = int(x)
        self.next = next
        self.random = random
"""

class Solution:
    def __init__(self):
        self.map = {}

    def copyRandomList(self, head: 'Optional[Node]') -> 'Optional[Node]':
        if head is None:
            return None
        if head in self.map:
            return self.map[head]

        copy = Node(head.val)
        self.map[head] = copy
        copy.next = self.copyRandomList(head.next)
        copy.random = self.map.get(head.random)
        return copy

#2nd way

"""
# Definition for a Node.
class Node:
    def __init__(self, x: int, next: 'Node' = None, random: 'Node' = None):
        self.val = int(x)
        self.next = next
        self.random = random
"""

class Solution:
    def copyRandomList(self, head: 'Optional[Node]') -> 'Optional[Node]':
        oldToCopy = {None: None}

        cur = head
        while cur:
            copy = Node(cur.val)
            oldToCopy[cur] = copy
            cur = cur.next
        cur = head
        while cur:
            copy = oldToCopy[cur]
            copy.next = oldToCopy[cur.next]
            copy.random = oldToCopy[cur.random]
            cur = cur.next
        return oldToCopy[head]


#3rd way

"""
# Definition for a Node.
class Node:
    def __init__(self, x: int, next: 'Node' = None, random: 'Node' = None):
        self.val = int(x)
        self.next = next
        self.random = random
"""

class Solution:
    def copyRandomList(self, head: 'Optional[Node]') -> 'Optional[Node]':
        oldToCopy = collections.defaultdict(lambda: Node(0))
        oldToCopy[None] = None

        cur = head
        while cur:
            oldToCopy[cur].val = cur.val
            oldToCopy[cur].next = oldToCopy[cur.next]
            oldToCopy[cur].random = oldToCopy[cur.random]
            cur = cur.next
        return oldToCopy[head]


#4th way


"""
# Definition for a Node.
class Node:
    def __init__(self, x: int, next: 'Node' = None, random: 'Node' = None):
        self.val = int(x)
        self.next = next
        self.random = random
"""

class Solution:
    def copyRandomList(self, head: 'Optional[Node]') -> 'Optional[Node]':
        if head is None:
            return None

        l1 = head
        while l1 is not None:
            l2 = Node(l1.val)
            l2.next = l1.next
            l1.next = l2
            l1 = l2.next

        newHead = head.next

        l1 = head
        while l1 is not None:
            if l1.random is not None:
                l1.next.random = l1.random.next
            l1 = l1.next.next

        l1 = head
        while l1 is not None:
            l2 = l1.next
            l1.next = l2.next
            if l2.next is not None:
                l2.next = l2.next.next
            l1 = l1.next

        return newHead


#5th way
"""
# Definition for a Node.
class Node:
    def __init__(self, x: int, next: 'Node' = None, random: 'Node' = None):
        self.val = int(x)
        self.next = next
        self.random = random
"""

class Solution:
    def copyRandomList(self, head: 'Optional[Node]') -> 'Optional[Node]':
        if head is None:
            return None

        l1 = head
        while l1:
            l2 = Node(l1.val)
            l2.next = l1.random
            l1.random = l2
            l1 = l1.next

        newHead = head.random

        l1 = head
        while l1:
            l2 = l1.random
            l2.random = l2.next.random if l2.next else None
            l1 = l1.next

        l1 = head
        while l1 is not None:
            l2 = l1.random
            l1.random = l2.next
            l2.next = l1.next.random if l1.next else None
            l1 = l1.next

        return newHead