feat: solve DaleStudy#290 with python

word-search-ii/EGON.py

@@ -0,0 +1,112 @@
+from typing import List
+from unittest import TestCase, main
+
+
+class Node:
+
+    def __init__(self, key, data=None):
+        self.key = key
+        self.data = data
+        self.children = {}
+
+
+class Trie:
+
+    def __init__(self):
+        self.root = Node(None)
+
+    def insert(self, word: str) -> None:
+        curr_node = self.root
+        for char in word:
+            if char not in curr_node.children:
+                curr_node.children[char] = Node(char)
+
+            curr_node = curr_node.children[char]
+
+        curr_node.data = word
+
+
+class Solution:
+    def findWords(self, board: List[List[str]], words: List[str]) -> List[str]:
+        return self.solve_trie_dfs(board, words)
+
+    """
+    * Constraints:
+        1. m == board.length
+        2. n == board[i].length
+        3. 1 <= m, n <= 12
+        4. board[i][j] is a lowercase English letter.
+        5. 1 <= words.length <= 3 * 104
+        6. 1 <= words[i].length <= 10
+        7. words[i] consists of lowercase English letters.
+        8. All the strings of words are unique.
+
+    Runtime: 6439 ms (Beats 26.38%)
+    Time Complexity: O(R * C * (4 ^ max L))
+        - word의 최대 길이를 max L, words의 길이를 K라 하면, trie에 words를 모두 insert하는데 O(max L * K), upper bound
+        - board의 각 grid에서 조회하는데 O(R * C)
+            - grid마다 dfs 호출하는데, dfs의 방향은 4곳이고, 호출 스택의 최대 깊이는 max L 이므로, * O(4 ^ max L)
+        > O(max L * K) + O(R * C) * O(4 ^ max L) ~= O(R * C * (4 ^ max L))
+
+    Memory: 19.04 MB (Beats 20.79%)
+    Space Complexity: O(max L * K)
+        - trie의 공간 복잡도는 O(max L * K), upper bound
+        - board의 각 grid에서 dfs를 호출하고, dfs 호출 스택의 최대 깊이는 max L 이므로 O(max L)
+        - result의 최대 크기는 words의 길이와 같으므로 O(K), upper bound
+        > O(max L * K) + O(max L) + O(K) ~= O(max L * K)
+    """
+    def solve_trie_dfs(self, board: List[List[str]], words: List[str]) -> List[str]:
+        MAX_R, MAX_C = len(board), len(board[0])
+        DIRS = [(0, 1), (1, 0), (0, -1), (-1, 0)]
+
+        trie = Trie()
+        for word in words:
+            trie.insert(word)
+
+        def dfs(curr: Node, r: int, c: int, path: str):
+            nonlocal result
+
+            if not (0 <= r < MAX_R and 0 <= c < MAX_C):
+                return
+
+            if board[r][c] == "#":
+                return
+
+            char = board[r][c]
+            if char not in curr.children:
+                return
+
+            post = curr.children[char]
+            if post.data:
+                result.add(post.data)
+
+            board[r][c] = "#"
+            for dir_r, dir_c in DIRS:
+                dfs(post, r + dir_r, c + dir_c, path + char)
+            board[r][c] = char
+
+        result = set()
+        for r in range(MAX_R):
+            for c in range(MAX_C):
+                if board[r][c] in trie.root.children:
+                    dfs(trie.root, r, c, "")
+
+        return list(result)
+
+
+class _LeetCodeTestCases(TestCase):
+    def test_1(self):
+        board = [["o", "a", "a", "n"], ["e", "t", "a", "e"], ["i", "h", "k", "r"], ["i", "f", "l", "v"]]
+        words = ["oath","pea","eat","rain"]
+        output = ["eat","oath"]
+        self.assertEqual(Solution.findWords(Solution(), board, words), output)
+
+    def test_2(self):
+        board = [["a","b"],["c","d"]]
+        words = ["abcb"]
+        output = []
+        self.assertEqual(Solution.findWords(Solution(), board, words), output)
+
+
+if __name__ == '__main__':
+    main()