Priority Queue 優先權佇列
- 2021.12.26
- Data Structure heqpq Priority Queue
定義 當 pop() 時，會遵守： queue的特性：先進先出（first in, first out） 優先權 大/小 的優先 pop （max/min-priority queue） 用 Binary Heap 實作 Priority Queue [Python] 使用 heapq
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Leetcode # 45. Jump Game II
- 2021.12.25
- Dynamic Programming Greedy Method LeetCode
https://leetcode.com/problems/jump-game-ii/ Solution (Dynamic Programming) class Solution: def jump(self, nums: List[int]) -> int: DP = [0] + [float("inf")]* (len(nums) - 1) for i in range(len(nums ...
Binary Method 二分法
- 2021.12.24
- Algorithm Binary Method / Divide and Conquer
分治法 Divide and Conquer 總是能夠將「問題 X 」拆分為「問題 A 」和「問題 B 」 滿足「問題 A 」+「問題 B 」=「問題 X 」 且能確定「問題 X 」的解只存在於「問題 A 」或「問題 B 」兩者其中之一 如果「問題 X 」的 brute force 解法之 time complexity 為 O(n) 則使用 binary method 的時間複雜度將減少為 O( ...
Leetcode # 210. Course Schedule II
https://leetcode.com/problems/course-schedule-ii/ Explanation 使用 in-degree 關鍵在於 優先提取 in-degree 為 0 的 vertex（即該 vertex 已無任何前導 vertex） vertex被提取時，調整其子 vertex 的 in-degree 當 graph 中有 loop 當 graph 中有 loop ...
[Python] list, set, dict, collections (deque, defaultdict, Counter)
- 2021.12.23
- collections Counter defaultdict deque dict frozenset list Python Queue set
list 常用操作 Operation Syntax ATC Append an item x to the last lst.append(x) O(1) Remove and return the last (most left) item in the list lst.pop() O(1) Remove and return the ith item in the list lst.pop ...
Leetcode # 5. Longest Palindromic Substring (Manacher’s Algorithm)
- 2021.12.22
- Algorithm Dynamic Programming LeetCode
https://leetcode.com/problems/longest-palindromic-substring/ Solution Dynamic Programming \begin{align*} & \text{定義 } P(i, j) \text{ 為：} \\ & P(i, j)= \begin{cases} True & \text{, if the s ...
Leetcode # 902. Numbers At Most N Given Digit Set
- 2021.12.22
- Dynamic Programming LeetCode
https://leetcode.com/problems/numbers-at-most-n-given-digit-set/ Solution class Solution: def atMostNGivenDigitSet(self, digits: List[str], n: int) -> int: n_str = str(n) l = len(n_str) dp = [0] * ...
Leetcode # 143. Reorder List
- 2021.12.22
- LeetCode Linked List
https://leetcode.com/problems/reorder-list/ Key point 使用一快一慢的pointer來找到length和middle node Solution class Solution: def reorderList(self, head: Optional[ListNode]) -> None: """ Do not return anythin ...
[Python] Sorting
概覽 Syntax Description Average Time Complexity Space Complexity list_b = sorted(list_a) 回傳排序好的新list O(n * log(n)); n = len(list_a) O(n) list_a.sort() 將list_a排序 O(n * log(n)) O(n) 常用auguments key 排序時以ke ...
Leetcode # 53. Maximum Subarray (Kadane’s Algorithm)
- 2021.12.09
- ★★ Medium Dynamic Programming Kadane’s Algorithm LeetCode
https://leetcode.com/problems/maximum-subarray/ Solution \begin{align} &\text{max_ending_here } := \mathop{\max}_{i \in [0, j]}\quad{\mathop{\sum}_{k=i}^j{nums[k]}} \\ &\text{max_so_far } := \ ...
