Create 79-Word-Search.py

Author: neetcode-gh

79-Word-Search.py

@@ -0,0 +1,25 @@
+class Solution:
+    def exist(self, board: List[List[str]], word: str) -> bool:
+        ROWS, COLS = len(board), len(board[0])
+        path = set()
+        
+        def dfs(r, c, i):
+            if i == len(word):
+                return True
+            if (min(r, c) < 0 or r >= ROWS or c >= COLS or
+                word[i] != board[r][c] or (r, c) in path):
+                return False
+            path.add((r, c))
+            res = (dfs(r + 1, c, i + 1) or
+                   dfs(r - 1, c, i + 1) or
+                   dfs(r, c + 1, i + 1) or
+                   dfs(r, c - 1, i + 1))
+            path.remove((r, c))
+            return res
+        
+        for r in range(ROWS):
+            for c in range(COLS):
+                if dfs(r, c, 0): return True
+        return False
+    
+    # O(n * m * 4^n)