Added Word Search (Backtracking) in Python

Python/backtracking/Word_Search.py

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+# Function to check if a word exists in a 2D board of characters.
+# Uses backtracking to explore possible paths in the grid.
+
+def word_search(board, word):
+
+    rows, cols = len(board), len(board[0])
+
+    # Backtracking function to explore each cell in the board
+    def backtrack(r, c, i):
+        # If we have matched all characters in the word
+        if i == len(word):
+            return True
+
+        # Check if the current position is out of bounds or does not match the current character
+        if r < 0 or c < 0 or r >= rows or c >= cols or board[r][c] != word[i]:
+            return False
+
+        # Temporarily mark the current cell as visited
+        temp = board[r][c]
+        board[r][c] = '#'  # mark as visited
+
+        # Explore all possible directions: down, up, right, left
+        found = (backtrack(r + 1, c, i + 1) or
+                 backtrack(r - 1, c, i + 1) or
+                 backtrack(r, c + 1, i + 1) or
+                 backtrack(r, c - 1, i + 1))
+
+        # Unmark the current cell to backtrack
+        board[r][c] = temp  # unmark
+        return found
+
+    # Iterate through each cell in the board
+    for r in range(rows):
+        for c in range(cols):
+            # Start backtracking from each cell
+            if backtrack(r, c, 0):
+                return True  # Word found in the board
+
+    return False  # Word not found in the board
+
+# Sample Usage:
+# Input: 2D board and a word to search
+# Example board:
+# [
+#     ['A', 'B', 'C', 'E'],
+#     ['S', 'F', 'C', 'S'],
+#     ['A', 'D', 'E', 'E']
+# ]
+# Example word: "ABCCED"
+
+# Input from user
+rows = int(input("Enter the number of rows in the board: "))
+cols = int(input("Enter the number of columns in the board: "))
+
+board = []
+print("Enter the board row by row (characters without spaces):")
+for _ in range(rows):
+    row = list(input().strip())
+    board.append(row)
+
+word = input("Enter the word to search for: ")
+
+# Call the function and print the result
+if word_search(board, word):
+    print("The word exists in the board.")
+else:
+    print("The word does not exist in the board.")