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0079-word-search/0079-word-search.py

@@ -0,0 +1,49 @@
+from collections import deque
+class Solution:
+    dx = [-1, 1, 0, 0]
+    dy = [0, 0, -1, 1]
+    ans = False
+
+    def backtracking(self, x, y, cnt = 0):
+        if self.ans:
+            return 
+
+        if cnt == len(self.word):
+            self.ans = True
+            return
+
+        for i in range(4):
+            nx, ny = x + self.dx[i], y + self.dy[i]
+
+            if nx < 0 or nx >= self.n or ny < 0 or ny >= self.m or self.vst[nx][ny]:
+                continue
+
+            if self.word[cnt] != self.board[nx][ny]:
+                continue
+
+            self.vst[nx][ny] = True
+            self.backtracking(nx, ny, cnt + 1)
+            self.vst[nx][ny] = False
+
+
+    def exist(self, board: List[List[str]], word: str) -> bool:
+        self.n, self.m = len(board), len(board[0])
+        self.word = word
+        self.vst = [[False] * self.m for _ in range(self.n)]
+        self.board = board
+
+        d = deque()
+        for i in range(self.n):
+            for j in range(self.m):
+                if word[0] == board[i][j]:
+                    d.append([i, j, 1])
+
+        while d:
+            x, y, cnt = d.pop()
+            self.vst[x][y] = True
+            self.backtracking(x, y, cnt)
+            self.vst[x][y] = False
+            if self.ans:
+                return True
+
+        return False