1 problem completed

word search.py

@@ -0,0 +1,33 @@
+class Solution:
+    def exist(self, board: List[List[str]], word: str) -> bool:
+        self.m=len(board)
+        self.n=len(board[0])
+
+        self.dirs=[[-1,0],[0,1],[1,0],[0,-1]]
+
+        for r in range(self.m):
+            for c  in range(self.n):
+                if self.helper(board,r,c,word,0):
+                    return True
+        return False
+
+    def helper(self,board,r,c,word,idx):
+        #base
+        if idx==len(word):
+            return True
+        if r<0 or c<0 or r==self.m or c==self.n or board[r][c]=='#':
+            return False
+        if board[r][c]!=word[idx]:
+            return False
+
+        board[r][c]='#'
+        #action
+        for dir in self.dirs:
+            i=r+dir[0]
+            j=c+dir[1]
+
+            if self.helper(board,i,j,word,idx+1):
+                return True
+        board[r][c]=word[idx]
+
+        return False