如何在字母矩阵中找到单词

def find_word(matrix, word):
    rows = len(matrix)
    cols = len(matrix[0])
    visited = [[False] * cols for _ in range(rows)]

    def backtrack(row, col, index):
        if index == len(word):
            return True

        if row < 0 or row >= rows or col < 0 or col >= cols:
            return False

        if visited[row][col] or matrix[row][col] != word[index]:
            return False

        visited[row][col] = True

        if (backtrack(row + 1, col, index + 1) or
            backtrack(row - 1, col, index + 1) or
            backtrack(row, col + 1, index + 1) or
            backtrack(row, col - 1, index + 1)):
            return True

        visited[row][col] = False
        return False

    for i in range(rows):
        for j in range(cols):
            if backtrack(i, j, 0):
                return True

    return False