Sync LeetCode submission Runtime - 168 ms (5.03%), Memory - 14.5 MB (100.00%)

Author: jimit105

0036-valid-sudoku/README.md

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+<p>Determine if a&nbsp;<code>9 x 9</code> Sudoku board&nbsp;is valid.&nbsp;Only the filled cells need to be validated&nbsp;<strong>according to the following rules</strong>:</p>
+
+<ol>
+	<li>Each row&nbsp;must contain the&nbsp;digits&nbsp;<code>1-9</code> without repetition.</li>
+	<li>Each column must contain the digits&nbsp;<code>1-9</code>&nbsp;without repetition.</li>
+	<li>Each of the nine&nbsp;<code>3 x 3</code> sub-boxes of the grid must contain the digits&nbsp;<code>1-9</code>&nbsp;without repetition.</li>
+</ol>
+
+<p><strong>Note:</strong></p>
+
+<ul>
+	<li>A Sudoku board (partially filled) could be valid but is not necessarily solvable.</li>
+	<li>Only the filled cells need to be validated according to the mentioned&nbsp;rules.</li>
+</ul>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+<img src="https://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/Sudoku-by-L2G-20050714.svg/250px-Sudoku-by-L2G-20050714.svg.png" style="height:250px; width:250px" />
+<pre>
+<strong>Input:</strong> board = 
+[[&quot;5&quot;,&quot;3&quot;,&quot;.&quot;,&quot;.&quot;,&quot;7&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;]
+,[&quot;6&quot;,&quot;.&quot;,&quot;.&quot;,&quot;1&quot;,&quot;9&quot;,&quot;5&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;]
+,[&quot;.&quot;,&quot;9&quot;,&quot;8&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;6&quot;,&quot;.&quot;]
+,[&quot;8&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;6&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;3&quot;]
+,[&quot;4&quot;,&quot;.&quot;,&quot;.&quot;,&quot;8&quot;,&quot;.&quot;,&quot;3&quot;,&quot;.&quot;,&quot;.&quot;,&quot;1&quot;]
+,[&quot;7&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;2&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;6&quot;]
+,[&quot;.&quot;,&quot;6&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;2&quot;,&quot;8&quot;,&quot;.&quot;]
+,[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;4&quot;,&quot;1&quot;,&quot;9&quot;,&quot;.&quot;,&quot;.&quot;,&quot;5&quot;]
+,[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;8&quot;,&quot;.&quot;,&quot;.&quot;,&quot;7&quot;,&quot;9&quot;]]
+<strong>Output:</strong> true
+</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> board = 
+[[&quot;8&quot;,&quot;3&quot;,&quot;.&quot;,&quot;.&quot;,&quot;7&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;]
+,[&quot;6&quot;,&quot;.&quot;,&quot;.&quot;,&quot;1&quot;,&quot;9&quot;,&quot;5&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;]
+,[&quot;.&quot;,&quot;9&quot;,&quot;8&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;6&quot;,&quot;.&quot;]
+,[&quot;8&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;6&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;3&quot;]
+,[&quot;4&quot;,&quot;.&quot;,&quot;.&quot;,&quot;8&quot;,&quot;.&quot;,&quot;3&quot;,&quot;.&quot;,&quot;.&quot;,&quot;1&quot;]
+,[&quot;7&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;2&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;6&quot;]
+,[&quot;.&quot;,&quot;6&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;2&quot;,&quot;8&quot;,&quot;.&quot;]
+,[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;4&quot;,&quot;1&quot;,&quot;9&quot;,&quot;.&quot;,&quot;.&quot;,&quot;5&quot;]
+,[&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;.&quot;,&quot;8&quot;,&quot;.&quot;,&quot;.&quot;,&quot;7&quot;,&quot;9&quot;]]
+<strong>Output:</strong> false
+<strong>Explanation:</strong> Same as Example 1, except with the <strong>5</strong> in the top left corner being modified to <strong>8</strong>. Since there are two 8&#39;s in the top left 3x3 sub-box, it is invalid.
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>board.length == 9</code></li>
+	<li><code>board[i].length == 9</code></li>
+	<li><code>board[i][j]</code> is a digit <code>1-9</code> or <code>&#39;.&#39;</code>.</li>
+</ul>

0036-valid-sudoku/solution.py

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+# Approach 1 - Hash Set
+
+# Time: O(N^2), Space: O(N^2)
+
+class Solution:
+    def isValidSudoku(self, board: List[List[str]]) -> bool:
+        N = 9
+        
+        # Create list of sets for each row, col and box
+        rows = [set() for _ in range(N)]
+        cols = [set() for _ in range(N)]
+        boxes = [set() for _ in range(N)]
+        
+        for r in range(N):
+            for c in range(N):
+                val = board[r][c]
+                
+                if val == '.':
+                    continue
+                    
+                if val in rows[r]:
+                    return False
+                rows[r].add(val)
+                
+                if val in cols[c]:
+                    return False
+                cols[c].add(val)
+                
+                idx = (r // 3) * 3 + c // 3
+                if val in boxes[idx]:
+                    return False
+                boxes[idx].add(val)
+                
+        return True
+                    
+                
+