동까의 코딩

https://leetcode.com/problems/sort-characters-by-frequency/description/ class Solution: def frequencySort(self, s: str) -> str: m = {} for c in s: if c not in m: m[c] = 1 else: m[c] += 1 li = sorted([(m[i], i) for i in m], reverse=True) res = [] for count, c in li: res.append(c * count) ..

https://leetcode.com/problems/find-the-original-array-of-prefix-xor/submissions/1289234381/ leetcode 문제사이트의 배열 문제입니다. class Solution: def findArray(self, pref: List[int]) -> List[int]: ans = [0] * len(pref) ans[0] = pref[0] for i in range(1, len(ans)): ans[i] = pref[i] ^ pref[i - 1] return ans

Leetcode에서 그래프 문제를 풀어보았습니다. https://leetcode.com/problems/reverse-odd-levels-of-binary-tree/description/  class Solution: def reverseOddLevels(self, root: Optional[TreeNode]) -> Optional[TreeNode]: nodes = [] level = [root] level_idx = 0 while level: if level_idx % 2 == 0: nodes.append(level) else: nodes.append(le..

leetcode의 dfs 문제를 풀어보았습니다. https://leetcode.com/problems/deepest-leaves-sum/submissions/1273992637/ 아직은 클래스로 구현하는것이 어렵지만 여러 문제를 많이 풀어봐야 할 것 같습니다. from collections import defaultdictclass Solution: def deepestLeavesSum(self, root: Optional[TreeNode]) -> int: nodelevel = defaultdict(list) def dfs(currentNode : TreeNode, level: int): if not nodelevel[level]: ..

오늘은 리트코드 사이트의 문제를 풀어보았습니다. https://leetcode.com/problems/smallest-number-in-infinite-set/description/   class SmallestInfiniteSet: def __init__(self): self.present = [True for _ in range(1002)] def popSmallest(self) -> int: for x in range(1, 1001): if self.present[x]: self.present[x] = False return x def addBack(self, num: int) -> N..