feat: Solve word-search-ii problem

Author: hu6r1s

word-search-ii/hu6r1s.py

@@ -0,0 +1,33 @@
+class Solution:
+    def findWords(self, board: List[List[str]], words: List[str]) -> List[str]:
+        n, m = len(board), len(board[0])
+        res = set()
+
+        trie = {}
+        for word in words:
+            node = trie
+            for ch in word:
+                node = node.setdefault(ch, {})
+            node['$'] = word
+
+        def dfs(x, y, node):
+            ch = board[x][y]
+            if ch not in node:
+                return
+            nxt = node[ch]
+
+            if '$' in nxt:
+                res.add(nxt['$'])
+
+            board[x][y] = "#"
+            for dx, dy in [(1,0), (-1,0), (0,1), (0,-1)]:
+                nx, ny = x + dx, y + dy
+                if 0 <= nx < n and 0 <= ny < m and board[nx][ny] != "#":
+                    dfs(nx, ny, nxt)
+            board[x][y] = ch
+
+        for i in range(n):
+            for j in range(m):
+                dfs(i, j, trie)
+
+        return list(res)