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437. Path Sum III # 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 = rightclass Solution: def pathSum(self, root: Optional[TreeNode], targetSum: int) -> int: count =0 def dfs(node, just_started, sub_sum): nonlocal count if node =..

1372. Longest ZigZag Path in a Binary Tree # 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 = rightclass Solution: def longestZigZag(self, root: Optional[TreeNode]) -> int: res = 0 def dfs(node, left2right, depth): nonlocal res ..

872. Leaf-Similar Trees 내 풀이# 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 = rightclass Solution: def getleaf(self, root): leaf1 = [] s1 = [(root, 1)] # node, depth max_depth = 1 while s1: node, depth = s1.pop() ..

206. Reverse Linked List https://leetcode.com/problems/reverse-linked-list/description/  나도 stack 으로 풀었으나, 제대로 못푼 느낌??# Definition for singly-linked list.# class ListNode:# def __init__(self, val=0, next=None):# self.val = val# self.next = nextclass Solution: def reverseList(self, head: Optional[ListNode]) -> Optional[ListNode]: # 스텍으로 푸는 법 stack = [] ..

2095. Delete the Middle Node of a Linked List # Definition for singly-linked list.# class ListNode:# def __init__(self, val=0, next=None):# self.val = val# self.next = nextclass Solution: def deleteMiddle(self, head: Optional[ListNode]) -> Optional[ListNode]: if not head or not head.next: return None one_step = head two_step = head.next.next..

649. Dota2 Senate class Solution: def predictPartyVictory(self, senate: str) -> str: r_q = deque() d_q = deque() for i, s in enumerate(senate): if s == "R": r_q.append(i) else: d_q.append(i) while r_q and d_q: d = d_q.popleft() r = r_q.popleft() if d  https://youtu.be/zZA5KskfMuQ?s..

933. Number of Recent Calls import collectionsclass RecentCounter: def __init__(self): self.q = collections.deque() self.q_len = 0 def ping(self, t: int) -> int: self.q.append(t) self.q_len +=1 while self.q[0]

2352. Equal Row and Column Pairs 해시맵 으로.. class Solution: def equalPairs(self, grid: List[List[int]]) -> int: """ grid [ [c1 c2 c3] r1 [c1 c2 c3] r2 [c1 c2 c3] ] r3 """ n = len(grid) row = {} for i in range(n): if tuple(grid[i]) in row: row[tuple(grid[i])] +=1 else: ..

643. Maximum Average Subarray I You are given an integer array nums consisting of n elements, and an integer k.Find a contiguous subarray whose length is equal to k that has the maximum average value and return this value. Any answer with a calculation error less than 10-5 will be accepted. Example 1:Input: nums = [1,12,-5,-6,50,3], k = 4Output: 12.75000Explanation: Maximum average is (12 - 5 - ..

1679. Max Number of K-Sum Pairs You are given an integer array nums and an integer k.In one operation, you can pick two numbers from the array whose sum equals k and remove them from the array.Return the maximum number of operations you can perform on the array. Example 1:Input: nums = [1,2,3,4], k = 5Output: 2Explanation: Starting with nums = [1,2,3,4]:- Remove numbers 1 and 4, then nums = [2,3..