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leetcode/problem/range-sum-query-2d-immutable.html
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@@ -4,15 +4,17 @@
<li>Calculate the <strong>sum</strong> of the elements of <code>matrix</code> inside the rectangle defined by its <strong>upper left corner</strong> <code>(row1, col1)</code> and <strong>lower right corner</strong> <code>(row2, col2)</code>.</li>
</ul>
<p>Implement the NumMatrix class:</p>
<p>Implement the <code>NumMatrix</code> class:</p>
<ul>
<li><code>NumMatrix(int[][] matrix)</code> Initializes the object with the integer matrix <code>matrix</code>.</li>
<li><code>int sumRegion(int row1, int col1, int row2, int col2)</code> Returns the <strong>sum</strong> of the elements of <code>matrix</code> inside the rectangle defined by its <strong>upper left corner</strong> <code>(row1, col1)</code> and <strong>lower right corner</strong> <code>(row2, col2)</code>.</li>
</ul>
<p>You must design an algorithm where <code>sumRegion</code> works on <code>O(1)</code> time complexity.</p>
<p>&nbsp;</p>
<p><strong>Example 1:</strong></p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/03/14/sum-grid.jpg" style="width: 415px; height: 415px;" />
<pre>
<strong>Input</strong>
@@ -35,7 +37,7 @@ numMatrix.sumRegion(1, 2, 2, 4); // return 12 (i.e sum of the blue rectangle)
<li><code>m == matrix.length</code></li>
<li><code>n == matrix[i].length</code></li>
<li><code>1 &lt;= m, n &lt;= 200</code></li>
<li><code>-10<sup>5</sup> &lt;= matrix[i][j] &lt;= 10<sup>5</sup></code></li>
<li><code>-10<sup>4</sup> &lt;= matrix[i][j] &lt;= 10<sup>4</sup></code></li>
<li><code>0 &lt;= row1 &lt;= row2 &lt; m</code></li>
<li><code>0 &lt;= col1 &lt;= col2 &lt; n</code></li>
<li>At most <code>10<sup>4</sup></code> calls will be made to <code>sumRegion</code>.</li>