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40 lines
1.5 KiB
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40 lines
1.5 KiB
HTML
<p>Given a <code>matrix</code> and a <code>target</code>, return the number of non-empty submatrices that sum to <font face="monospace">target</font>.</p>
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<p>A submatrix <code>x1, y1, x2, y2</code> is the set of all cells <code>matrix[x][y]</code> with <code>x1 <= x <= x2</code> and <code>y1 <= y <= y2</code>.</p>
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<p>Two submatrices <code>(x1, y1, x2, y2)</code> and <code>(x1', y1', x2', y2')</code> are different if they have some coordinate that is different: for example, if <code>x1 != x1'</code>.</p>
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<p> </p>
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<p><strong>Example 1:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2020/09/02/mate1.jpg" style="width: 242px; height: 242px;" />
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<pre>
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<strong>Input:</strong> matrix = [[0,1,0],[1,1,1],[0,1,0]], target = 0
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<strong>Output:</strong> 4
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<strong>Explanation:</strong> The four 1x1 submatrices that only contain 0.
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</pre>
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<p><strong>Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> matrix = [[1,-1],[-1,1]], target = 0
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<strong>Output:</strong> 5
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<strong>Explanation:</strong> The two 1x2 submatrices, plus the two 2x1 submatrices, plus the 2x2 submatrix.
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</pre>
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<p><strong>Example 3:</strong></p>
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<pre>
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<strong>Input:</strong> matrix = [[904]], target = 0
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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>1 <= matrix.length <= 100</code></li>
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<li><code>1 <= matrix[0].length <= 100</code></li>
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<li><code>-1000 <= matrix[i] <= 1000</code></li>
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<li><code>-10^8 <= target <= 10^8</code></li>
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</ul>
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