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35 lines
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35 lines
1.5 KiB
HTML
<p>A <code>3 x 3</code> magic square is a <code>3 x 3</code> grid filled with distinct numbers <strong>from </strong><code>1</code><strong> to </strong><code>9</code> such that each row, column, and both diagonals all have the same sum.</p>
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<p>Given a <code>row x col</code> <code>grid</code> of integers, how many <code>3 x 3</code> "magic square" subgrids are there? (Each subgrid is contiguous).</p>
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<p> </p>
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<p><strong class="example">Example 1:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2020/09/11/magic_main.jpg" style="width: 322px; height: 242px;" />
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<pre>
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<strong>Input:</strong> grid = [[4,3,8,4],[9,5,1,9],[2,7,6,2]]
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<strong>Output:</strong> 1
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<strong>Explanation: </strong>
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The following subgrid is a 3 x 3 magic square:
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<img alt="" src="https://assets.leetcode.com/uploads/2020/09/11/magic_valid.jpg" style="width: 242px; height: 242px;" />
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while this one is not:
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<img alt="" src="https://assets.leetcode.com/uploads/2020/09/11/magic_invalid.jpg" style="width: 242px; height: 242px;" />
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In total, there is only one magic square inside the given grid.
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</pre>
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<p><strong class="example">Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> grid = [[8]]
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<strong>Output:</strong> 0
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</pre>
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<p> </p>
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<p><strong>Constraints:</strong></p>
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<ul>
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<li><code>row == grid.length</code></li>
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<li><code>col == grid[i].length</code></li>
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<li><code>1 <= row, col <= 10</code></li>
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<li><code>0 <= grid[i][j] <= 15</code></li>
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</ul>
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