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208. Implement Trie (Prefix Tree) https://youtu.be/oobqoCJlHA0?si=rB7vqpOg4d0DiFd1 https://youtu.be/j7Zkw5XWe_Q?si=-yC7nuoxBULmLBuD 이 문제는 Trie(트라이) 자료 구조를 구현하는 것입니다. Trie는 문자열을 효율적으로 저장하고 검색하기 위해 사용되는 트리 형태의 자료 구조입니다. 이 자료 구조는 주로 자동완성, 단어 검색, 접두사 검색과 같은 작업에서 사용됩니다.  Code  # TrieNode 클래스: Trie의 각 노드를 정의class TrieNode: def __init__(self): self.children = {} # 자식 노드를 저장할 해시맵. 키는 문자, 값은 T..

1318. Minimum Flips to Make a OR b Equal to c  Given 3 positives numbers a, b and c. Return the minimum flips required in some bits of a and b to make ( a OR b == c ). (bitwise OR operation).Flip operation consists of change any single bit 1 to 0 or change the bit 0 to 1 in their binary representation. Example 1:Input: a = 2, b = 6, c = 5Output: 3Explanation: After flips a = 1 , b = 4 , c = 5 su..

136. Single Number class Solution: def singleNumber(self, nums: List[int]) -> int: # 2번 나온거는 무시하고, 1번 나온것만 찾음 # You must implement a solution with a linear runtime complexity and use only constant extra space. # 시간: O(n), 공간: O(1) 으로 풀어야 함 # for 루프 여러개? 단일 변수 여러개? # xor 하면(^) 2번 계산한건 0으로 사라짐 res = nums[0] for i in range(1, len(nums)): ..

338. Counting Bits Given an integer n, return an array ans of length n + 1 such that for each i (0  ans[i] is the number of 1's in the binary representation of i. Example 1:Input: n = 2Output: [0,1,1]Explanation:0 --> 01 --> 12 --> 10Example 2:Input: n = 5Output: [0,1,1,2,1,2]Explanation:0 --> 01 --> 12 --> 103 --> 114 --> 1005 --> 101 Constraints:0  Follow up:It is very easy to come up with a s..

714. Best Time to Buy and Sell Stock with Transaction Fee https://youtu.be/cUsPoH5DG1Q?si=vWqiiqYgUO8o6U1N Code class Solution: def maxProfit(self, prices: List[int], fee: int) -> int: n = len(prices) # buy[i]: i번째 날에 주식을 구매한 상태에서의 최대 이익 # sell[i]: i번째 날에 주식을 판매한 상태에서의 최대 이익 buy = [0] * n sell = [0] * n # 초기값: # 첫 번째 날에 주식을 구매한 경우: -prices[0] ..

문제 링크 : 1143. Longest Common Subsequence https://youtu.be/Ua0GhsJSlWM?si=-h73SwkVPoCVziy6  코드  class Solution: def longestCommonSubsequence(self, text1: str, text2: str) -> int: dp = [[0 for j in range(len(text2)+1)] for i in range(len(text1)+1)] for i in range(len(text1)-1, -1, -1): for j in range(len(text2)-1, -1, -1): if text1[i] == text2[j]: ..

62. Unique Paths 문제62. Unique PathsThere is a robot on an m x n grid. The robot is initially located at the top-left corner (i.e., grid[0][0]). The robot tries to move to the bottom-right corner (i.e., grid[m - 1][n - 1]). The robot can only move either down or right at any point in time.Given the two integers m and n, return the number of possible unique paths that the robot can take to reach t..

문제790. Domino and Tromino Tiling You have two types of tiles: a 2 x 1 domino shape and a tromino shape. You may rotate these shapes.Given an integer n, return the number of ways to tile an 2 x n board. Since the answer may be very large, return it modulo 109 + 7.In a tiling, every square must be covered by a tile. Two tilings are different if and only if there are two 4-directionally adjacent ce..

문제198. House Robber You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security systems connected and it will automatically contact the police if two adjacent houses were broken into on the same night.Given an integer array nums representing ..