<p>You are given an <code>m x n</code> matrix <code>board</code>, representing the<strong> current </strong>state of a crossword puzzle. The crossword contains lowercase English letters (from solved words), <code>&#39; &#39;</code> to represent any <strong>empty </strong>cells, and <code>&#39;#&#39;</code> to represent any <strong>blocked</strong> cells.</p>

<p>A word can be placed<strong> horizontally</strong> (left to right <strong>or</strong> right to left) or <strong>vertically</strong> (top to bottom <strong>or</strong> bottom to top) in the board if:</p>

<ul>
	<li>It does not occupy a cell containing the character <code>&#39;#&#39;</code>.</li>
	<li>The cell each letter is placed in must either be <code>&#39; &#39;</code> (empty) or <strong>match</strong> the letter already on the <code>board</code>.</li>
	<li>There must not be any empty cells <code>&#39; &#39;</code> or other lowercase letters <strong>directly left or right</strong><strong> </strong>of the word if the word was placed <strong>horizontally</strong>.</li>
	<li>There must not be any empty cells <code>&#39; &#39;</code> or other lowercase letters <strong>directly above or below</strong> the word if the word was placed <strong>vertically</strong>.</li>
</ul>

<p>Given a string <code>word</code>, return <code>true</code><em> if </em><code>word</code><em> can be placed in </em><code>board</code><em>, or </em><code>false</code><em> <strong>otherwise</strong></em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/10/04/crossword-ex1-1.png" style="width: 478px; height: 180px;" />
<pre>
<strong>Input:</strong> board = [[&quot;#&quot;, &quot; &quot;, &quot;#&quot;], [&quot; &quot;, &quot; &quot;, &quot;#&quot;], [&quot;#&quot;, &quot;c&quot;, &quot; &quot;]], word = &quot;abc&quot;
<strong>Output:</strong> true
<strong>Explanation:</strong> The word &quot;abc&quot; can be placed as shown above (top to bottom).
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/10/04/crossword-ex2-1.png" style="width: 180px; height: 180px;" />
<pre>
<strong>Input:</strong> board = [[&quot; &quot;, &quot;#&quot;, &quot;a&quot;], [&quot; &quot;, &quot;#&quot;, &quot;c&quot;], [&quot; &quot;, &quot;#&quot;, &quot;a&quot;]], word = &quot;ac&quot;
<strong>Output:</strong> false
<strong>Explanation:</strong> It is impossible to place the word because there will always be a space/letter above or below it.</pre>

<p><strong class="example">Example 3:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/10/04/crossword-ex3-1.png" style="width: 478px; height: 180px;" />
<pre>
<strong>Input:</strong> board = [[&quot;#&quot;, &quot; &quot;, &quot;#&quot;], [&quot; &quot;, &quot; &quot;, &quot;#&quot;], [&quot;#&quot;, &quot; &quot;, &quot;c&quot;]], word = &quot;ca&quot;
<strong>Output:</strong> true
<strong>Explanation:</strong> The word &quot;ca&quot; can be placed as shown above (right to left). 
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>m == board.length</code></li>
	<li><code>n == board[i].length</code></li>
	<li><code>1 &lt;= m * n &lt;= 2 * 10<sup>5</sup></code></li>
	<li><code>board[i][j]</code> will be <code>&#39; &#39;</code>, <code>&#39;#&#39;</code>, or a lowercase English letter.</li>
	<li><code>1 &lt;= word.length &lt;= max(m, n)</code></li>
	<li><code>word</code> will contain only lowercase English letters.</li>
</ul>

'''
Task: decide if we can place the word in board, return True/False
    1. left <-> right, up <-> down
    2. each letter: put on " " or match letter
    3. no "" or otherletter(outside word) 
        horizontal: take one row -> must start from 0th col in a row, end at n-1 row _ whicj are non_#
        vertically: take one col -> start from 0th row in col, end at m-1 row
    4. can't put on '#"

    constraints;
    m * n > 1 -> no empty board
    word_len < max(m, n) --> it might exceed a row/ col


Thoughts:
Time complexity: O(mn), space: O(1)

[0][] -> row
[][0] -> col
l = len(words)
if l > m: only check cols
if l > n: only check rows
we check each row: if can put and reach word end -> return True
    check:
        if "" or match: go to next ch in word; else:stop and chenck next row
we check each col: if can put and reach word end -> return
otherwise return False
'''

class Solution:
    def placeWordInCrossword(self, board: List[List[str]], word: str) -> bool:
        m, n = len(board), len(board[0])
        l = len(word)
        reversed_word = word[::-1]

        def canPut(s, word):
            if len(s) != l:
                return False

            i, j = 0, 0
            while i < len(s) and j < l:
                if s[i] == " " or s[i] == word[j]:
                    i += 1
                    j += 1
                else:
                    return False
            return True


        if l <= n:
            for row in range(m):
                row_str = ''.join(board[row])
                # row_str = row_str.lstrip('#')
                # row_str = row_str.rstrip('#')
                for s in row_str.split('#'):
                # row_str = row_str.rsplit('#')[-1] # keep everything after the last #
                    if canPut(s, word) or canPut(s, reversed_word):
                        return True
        
        if l <= m:
            for col in range(n):
                curcol = [board[i][col] for i in range(m)]
                col_str = ''.join(curcol)
                # col_str = col_str.lstrip('#')
                # col_str = col_str.rstrip('#')
                # col_str = col_str.rsplit('#', 1)[-1]
                for s in col_str.split('#'):
                    if canPut(s, word) or canPut(s, reversed_word):
                        return True
        return False

        
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