solve: word search

Author: sounmind

word-search/evan.py

@@ -0,0 +1,40 @@
+from typing import List
+
+
+class Solution:
+    def exist(self, board: List[List[str]], word: str) -> bool:
+        def dfs(row, col, k):
+            if k == len(word):
+                return True
+
+            # out of range
+            if row < 0 or row >= len(board) or col < 0 or col >= len(board[0]):
+                return False
+
+            # char not found
+            if board[row][col] != word[k]:
+                return False
+
+            temp = board[row][col]
+
+            # mark visited char
+            board[row][col] = None
+
+            result = (
+                dfs(row + 1, col, k + 1)  # top
+                or dfs(row - 1, col, k + 1)  # bottom
+                or dfs(row, col + 1, k + 1)  # right
+                or dfs(row, col - 1, k + 1)  # left
+            )
+
+            # restore char
+            board[row][col] = temp
+
+            return result
+
+        for row in range(len(board)):
+            for col in range(len(board[0])):
+                if dfs(row, col, 0):
+                    return True
+
+        return False