0203leetcode brushes 5 python questions

Sword refers to offer16

Title description:
Implement the function double Power(double base, int exponent), and find the exponent power of base. Do not use library functions, and do not need to consider the issue of large numbers.

Example:
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Answer:

class Solution:
    def myPow(self, x: float, n: int) -> float:
        if x == 0:
            return 0
        res = 1
        if n < 0:
            x, n = 1 / x, -n
        while n:
            if n & 1: 
                res *= x
            x *= x
            n >>= 1
        return res

Sword refers to offer18

Title description:
Given the head pointer of the singly linked list and the value of a node to be deleted, define a function to delete the node.
Return the head node of the deleted linked list.

Example:
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answer:

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
class Solution:
    def deleteNode(self, head: ListNode, val: int) -> ListNode:
        cur=head
        if cur.val==val:
            return head.next
        while cur:
            if cur.next.val==val:
                cur.next=cur.next.next
                return head
            cur=cur.next

Sword refers to offer24

Title description:
Define a function, input the head node of a linked list, reverse the linked list and output the head node of the reversed linked list.

Example:
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Answer:

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def reverseList(self, head: ListNode) -> ListNode:
        res=None
        while head:
            res,res.next,head=head,res,head.next
        return res

Sword refers to offer26

Title description:
Enter two binary trees A and B to determine whether B is a substructure of A. (It is agreed that an empty tree is not a substructure of any tree)
B is a substructure of A, that is, A has the same structure and node value as B.
For example:
given tree A:

 3
/ \

45
/
12
given tree B:
. 4
/
. 1
returns true, because a subtree B and A have the same configuration and the node values.

Example:
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Answer:

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def isSubStructure(self, A: TreeNode, B: TreeNode) -> bool:
        if not A or not B:
            return False
        return self.isInclude(A, B) or self.isSubStructure(A.left, B) or self.isSubStructure(A.right, B)

    def isInclude(self, A, B):
        if not B:
            return True
        if not A:
            return False
        if A.val != B.val:
            return False
        return self.isInclude(A.left, B.left) and self.isInclude(A.right, B.right)

Sword refers to offer27

Topic description:
Please complete a function, input a binary tree, and the function outputs its mirror image.
Such as input:
4
/
27
/ \ /
1369
image output:
4
/
72
/ \ /
9631

Example:
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Answer:

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def mirrorTree(self, root: TreeNode) -> TreeNode:
        if root==None:
            return None

        root.left,root.right=root.right,root.left
        self.mirrorTree(root.left)
        self.mirrorTree(root.right)
        return root