- Word Search DaleStudy#255

Author: ayosecu

word-search/ayosecu.py

@@ -0,0 +1,52 @@
+from typing import List
+
+class Solution:
+    """
+        - Time Complexity: O(m*n*3^w)
+            - m = len(board), n = len(board[0]), w = len(word)
+            - m * n => finding start point
+            - 3^w => There are three ways for visiting recursively until find a word
+        - Space Complexity: O(w)
+            - The sum of stack's space => The depth of dfs => len(word)
+    """
+    def exist(self, board: List[List[str]], word: str) -> bool:
+        m, n = len(board), len(board[0])
+        
+        # DFS approach
+        def dfs(i, j, leng):
+            if leng == len(word):
+                # Found!
+                return True
+            
+            if not (0 <= i < m and 0 <= j < n) or board[i][j] != word[leng]:
+                # Wrong position or Not matched
+                return False
+
+            temp = board[i][j]  # Backup
+            board[i][j] = "#"   # Visited
+            for dx, dy in [(1, 0), (0, 1), (-1, 0), (0, -1)]:
+                if dfs(i + dx, j + dy, leng + 1):
+                    return True
+            board[i][j] = temp  # Restore
+
+            return False
+        
+        # Finding Start Point
+        for i in range(m):
+            for j in range(n):
+                if word[0] == board[i][j]:
+                    if dfs(i, j, 0):
+                        return True
+    
+        return False
+
+tc = [
+        ([["A","B","C","E"],["S","F","C","S"],["A","D","E","E"]], "ABCCED", True),
+        ([["A","B","C","E"],["S","F","C","S"],["A","D","E","E"]], "SEE", True),
+        ([["A","B","C","E"],["S","F","C","S"],["A","D","E","E"]], "ABCB", False)
+]
+
+for i, (board, word, e) in enumerate(tc, 1):
+    sol = Solution()
+    r = sol.exist(board, word)
+    print(f"TC {i} is Passed!" if r == e else f"TC {i} is Failed! - Expected: {e}, Result: {r}")