Grind 75 Python 做題記錄 53. Maximum Subarray Grind 75 連結 Leetcode 題目連結 實測起來if比max快一些。 import math class Solution: def maxSubArray(self, nums: List[int]) -> int: # Kadane's Algorithm 卡登算法 # 定義全局最大和與局部最大和 global_max_sum = -math.inf local_max_sum = 0

Grind 75 Python 做題記錄 232. Implement Queue using Stacks Grind 75 連結 Leetcode 題目連結 class MyQueue: def __init__(self): self.stack1 = list() self.stack2 = list() def push(self, x: int) -> None: # Push 的時候放入 Stack1 self.stack1.append(x) def pop(self) -> int: # Pop 的時候，如果 Stack2 存在元素，先從 Stack2 倒出 if

Grind 75 Python 做題記錄 110. Balanced Binary Tree Grind 75 連結 Leetcode 題目連結 # Definition for a binary tree node. # class TreeNode: # def __init__(self, val=0, left=None, right=None): # self.val = val # self.left = left # self.right = right class Solution: def isBalanced(self, root: Optional[TreeNode]) -> bool: # 深度優先搜索函數 def dfs(root: Optional[TreeNode]): # 如

Grind 75 Python 做題記錄 141. Linked List Cycle Grind 75 連結 Leetcode 題目連結 # Definition for singly-linked list. # class ListNode: # def __init__(self, x): # self.val = x # self.next = None class Solution: def hasCycle(self, head: Optional[ListNode]) -> bool: # 快慢指針 fast = slow = head # 快針未觸底 while fast and fast.next: slow =

Grind 75 Python 做題記錄 235. Lowest Common Ancestor of a Binary Search Tree Grind 75 連結 Leetcode 題目連結 # Definition for a binary tree node. # class TreeNode: # def __init__(self, x): # self.val = x # self.left = None # self.right = None class Solution: def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode': # 如果走到底仍

Grind 75 Python 做題記錄 733. Flood Fill Grind 75 連結 Leetcode 題目連結 class Solution: def floodFill(self, image: List[List[int]], sr: int, sc: int, color: int) -> List[List[int]]: # 取得寬度與高度 row_len:int = len(image) col_len:int = len(image[0]) # 取得起點顏色 origin_color = image[sr][sc] # 如果起點顏色為目標顏色，

Grind 75 Python 做題記錄 704. Binary Search Grind 75 連結 Leetcode 題目連結 class Solution: def search(self, nums: List[int], target: int) -> int: # 二分搜索的左右指標設定 left = 0 right = len(nums)-1 # 建立循環條件 while left <= right: # 計算中央值 mid = (left + right)//2 #

Grind 75 Python 做題記錄 242. Valid Anagram Grind 75 連結 Leetcode 題目連結 class Solution: def isAnagram(self, s: str, t: str) -> bool: # 假如字串長度不同，回傳 False if len(s) != len(t): return False # 假如轉換成集合不同，回傳 False s_set:set = set(s) if s_set != set(t): return

Grind 75 Python 做題記錄 226. Invert Binary Tree Grind 75 連結 Leetcode 題目連結 # Definition for a binary tree node. # class TreeNode: # def __init__(self, val=0, left=None, right=None): # self.val = val # self.left = left # self.right = right class Solution: def invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]: # 假如傳入節點為空，終止遞迴

Grind 75 Python 做題記錄 125. Valid Palindrome Grind 75 連結 Leetcode 題目連結 class Solution: def isPalindrome(self, s: str) -> bool: # 取得統一小寫，並且去除標點的字串 clean_string : str = "".join(char.lower() for char in s if char.isalnum()) # 檢查字串是否等於反轉後的字串

Grind 75 Python 做題記錄 121. Best Time to Buy and Sell Stock Grind 75 連結 Leetcode 題目連結 import math class Solution: def maxProfit(self, prices: List[int]) -> int: # 定義最小價格 min_price:int = math.inf # 定義最大收益 max_profix:int = 0 # 遍歷價格 for current_price in prices: # 假如當前是最

Grind 75 Python 做題記錄 21. Merge Two Sorted Lists Grind 75 連結 Leetcode 題目連結 # Definition for singly-linked list. # class ListNode: # def __init__(self, val=0, next=None): # self.val = val # self.next = next class Solution: def mergeTwoLists(self, list1: Optional[ListNode], list2: Optional[ListNode]) -> Optional[ListNode]: # 建立虛擬頭部 dummy_head = ListNode() # 當前頭部節點 current_node

Grind 75 Python 做題記錄 20. Valid Parentheses Grind 75 連結 Leetcode 題目連結 class Solution: def isValid(self, s: str) -> bool: # 若為空字串直接返回 if len(s) == 0: return True # 建立括弧對的紀錄 pari_dict:dict = { ")":"(", "}":"{", "]":"[" } # 建立 stack stack = list() # 遍歷字

Grind 75 Python 做題記錄 1. Two Sum Grind 75 連結 Leetcode 題目連結 # enumerate class Solution: def twoSum(self, nums: List[int], target: int) -> List[int]: # 建立快取 key 為數值差值，Value 為 index cache: dict = dict() # 遍歷 nums for k,v in enumerate(nums): # 找到差值 diff:int = target

Grind 75 Python 做題記錄 67. Add Binary Grind 75 連結 Leetcode 題目連結 位元加法 class Solution: def addBinary(self, a: str, b: str) -> str: # 初始化結果列表、進位(carry)和指標(i, j) result = [] carry = 0 i, j = len(a) - 1,

Grind 75 Python 做題記錄 169. Majority Element Grind 75 連結 Leetcode 題目連結 import collections class Solution: def majorityElement(self, nums: List[int]) -> int: # Boyer-Moore 算法 # 記數 count = 0 # 候選人 can = None # 遍歷 List for num in nums: # 假如記數為 0，則記錄候選人 if count

Grind 75 Python 做題記錄 206. Reverse Linked List Grind 75 連結 Leetcode 題目連結 # Definition for singly-linked list. # class ListNode: # def __init__(self, val=0, next=None): # self.val = val # self.next = next class Solution: def reverseList(self, head: Optional[ListNode]) -> Optional[ListNode]: # 前一個指標 prev = None # 當前指標 curr = head # 遍歷串

Grind 75 Python 做題記錄 409. Longest Palindrome Grind 75 連結 Leetcode 題目連結 import collections class Solution: def longestPalindrome(self, s: str) -> int: # 用 collections.Counter(s) 取得每個字元出現次數建立成 dict() # 用 .values() 取得值 # 並且只取出現為奇數的字元 # 計算奇數

Grind 75 Python 做題記錄 70. Climbing Stairs Grind 75 連結 Leetcode 題目連結 class Solution: def climbStairs(self, n: int) -> int: # 記錄每一層樓梯的步驟數 way_dict = dict() # 初始值 way_dict[0] = 0 way_dict[1] = 1 # 走到二階有一次一階與一次兩階 way_dict[2] = 2

Grind 75 Python 做題記錄 383. Ransom Note Grind 75 連結 Leetcode 題目連結 答題 class Solution: def canConstruct(self, ransomNote: str, magazine: str) -> bool: # 將重複字串過濾，變成一個不重複list r_list = list(set(ransomNote)) # 遍歷 List for i in r_list: # 檢查每個字字數

Grind 75 Python 做題記錄 278. First Bad Version Grind 75 連結 Leetcode 題目連結 答題 # The isBadVersion API is already defined for you. # def isBadVersion(version: int) -> bool: class Solution: def firstBadVersion(self, n: int) -> int: # 最初版本號 left = 1 # 最終版本號 right = n # 二分搜索條件

Grind 75 Python 做題記錄 543. Diameter of Binary Tree Grind 75 連結 Leetcode 題目連結 答題 # Definition for a binary tree node. # class TreeNode: # def __init__(self, val=0, left=None, right=None): # self.val = val # self.left = left # self.right = right class Solution: def diameterOfBinaryTree(self, root: Optional[TreeNode]) -> int: # 儲存當前最大寬度 self.max_diameter =

Grind 75 Python 做題記錄 104. Maximum Depth of Binary Tree Grind 75 連結 Leetcode 題目連結 # Definition for a binary tree node. # class TreeNode: # def __init__(self, val=0, left=None, right=None): # self.val = val # self.left = left # self.right = right class Solution: def maxDepth(self, root: Optional[TreeNode]) -> int: # 觸底返 0 if not root: return 0 # 取

Grind 75 Python 做題記錄 876. Middle of the Linked List Grind 75 連結 Leetcode 題目連結 # Definition for singly-linked list. # class ListNode: # def __init__(self, val=0, next=None): # self.val = val # self.next = next class Solution: def middleNode(self, head: Optional[ListNode]) -> Optional[ListNode]: # 建立快慢針 fast = slow = head # 快針遍歷，快針

Grind 75 Python 做題記錄 217. Contains Duplicate Grind 75 連結 Leetcode 題目連結 答題 class Solution: def containsDuplicate(self, nums: List[int]) -> bool: # Set 長度與字串長度不同，代表有重複 return len(set(nums)) != len(nums)