79

Author: Jeldo

word-search/jeldo.py

@@ -0,0 +1,29 @@
+class Solution:
+    # (O(m*n))
+    def exist(self, board: List[List[str]], word: str) -> bool:
+        dirs = [(0, 1), (1, 0), (0, -1), (-1, 0)]
+        result = False
+
+        def dfs(i, j, visited, w):
+            nonlocal result
+            if (i, j) in visited:
+                return
+            if not (0 <= i < len(board)) or not (0 <= j < len(board[0])):
+                return
+            w += board[i][j]
+            if not (word[:len(w)] == w):
+                return
+            visited.add((i, j))
+            if w == word:
+                result = True
+                return
+            for d in dirs:
+                dfs(i + d[0], j + d[1], visited, w)
+            visited.remove((i, j))  # backtracking
+
+        for i in range(len(board)):
+            for j in range(len(board[0])):
+                dfs(i, j, set(), "")
+                if result:
+                    return True
+        return False