LeetCode word search

word_search.py

class Solution:
    # Allows us to do "for coordinate in self"
    def __iter__(self): return (
        (row, column)
        for row in range(self.rows)
        for column in range(self.columns)
    )
    
    # Allows us to do "self [coordinate]"
    def __getitem__(self, coordinate): return self.board [coordinate [0]] [coordinate [1]]
    
    # Detects if an answer exists. Returns true or false
    def exist(self, board, word) -> bool:
        self.board = board
        self.target = word
        self.rows = len(board)
        self.columns = len(board [0])
        self.length = len(word) - 1
        if (self.rows * self.columns) < len(word): return False
        
        for coordinate in self.search_for_letter(word [0]): 
            if self [coordinate] == self.target: return True
            if self.recurse(1, coordinate, visited = {coordinate}): 
                return True
        else: 
            return False
        
    # Tries to find the letter at "index" from "coordinate"
    # "visited" is the set of all visited coordinates, so it can't go back 
    def recurse(self, index, coordinate, visited = set()):
        # print(f"Trying to find {self.target [index]} from {coordinate} with {visited}")
        for neighbor in self.get_neighbors(coordinate): 
            if self [neighbor] == self.target [index] and neighbor not in visited:
                # print(f"Visiting {self.target [index]} at {neighbor}")
                # print(f"  Already visited: {visited}")
                if (
                    index == self.length
                    or self.recurse(index + 1, neighbor, visited.union({neighbor}))
                ):
                    # print(f"THIS IS IT. FOUND {self.target [index]} at {neighbor}")
                    return True
        else: 
            # print(f"Could not find {self.target [index]} from {coordinate}")
            return False
        
    # Returns the coordinate for a given letter. May return more than one. 
    def search_for_letter(self, target_letter): return (
        coordinate
        for coordinate in self
        if self [coordinate] == target_letter
    )
    
    # Gets all (valid) neighbors for a given coordinate
    def get_neighbors(self, coordinate): 
        result = []
        if (coordinate [0] != 0): 
            result.append( (coordinate [0] - 1, coordinate [1]) )
        if coordinate [0] != self.rows - 1:
            result.append( (coordinate [0] + 1, coordinate [1]) )
        if coordinate [1] != 0: 
            result.append( (coordinate [0], coordinate [1] - 1) )
        if coordinate [1] != self.columns - 1: 
            result.append( (coordinate [0], coordinate [1] + 1) )
        return result