Package g0301_0400.s0304_range_sum_query_2d_immutable

Class NumMatrix

java.lang.Object

g0301_0400.s0304_range_sum_query_2d_immutable.NumMatrix

public class NumMatrix
extends Object

304 - Range Sum Query 2D - Immutable.<p>Medium</p> <p>Given a 2D matrix <code>matrix</code>, handle multiple queries of the following type:</p> <ul> <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> <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><strong>Example 1:</strong></p> <p><img src="https://assets.leetcode.com/uploads/2021/03/14/sum-grid.jpg" alt="" /></p> <p><strong>Input</strong></p> <pre><code> [&quot;NumMatrix&quot;, &quot;sumRegion&quot;, &quot;sumRegion&quot;, &quot;sumRegion&quot;] [[[[3, 0, 1, 4, 2], [5, 6, 3, 2, 1], [1, 2, 0, 1, 5], [4, 1, 0, 1, 7], [1, 0, 3, 0, 5]]], [2, 1, 4, 3], [1, 1, 2, 2], [1, 2, 2, 4]] </code></pre> <p><strong>Output:</strong> [null, 8, 11, 12]</p> <p><strong>Explanation:</strong></p> <pre><code> NumMatrix numMatrix = new NumMatrix([[3, 0, 1, 4, 2], [5, 6, 3, 2, 1], [1, 2, 0, 1, 5], [4, 1, 0, 1, 7], [1, 0, 3, 0, 5]]); numMatrix.sumRegion(2, 1, 4, 3); // return 8 (i.e sum of the red rectangle) numMatrix.sumRegion(1, 1, 2, 2); // return 11 (i.e sum of the green rectangle) numMatrix.sumRegion(1, 2, 2, 4); // return 12 (i.e sum of the blue rectangle) </code></pre> <p><strong>Constraints:</strong></p> <ul> <li><code>m == matrix.length</code></li> <li><code>n == matrix[i].length</code></li> <li><code>1 <= m, n <= 200</code></li> <li><code>-10⁵ <= matrix[i][j] <= 10⁵</code></li> <li><code>0 <= row1 <= row2 < m</code></li> <li><code>0 <= col1 <= col2 < n</code></li> <li>At most <code>10⁴</code> calls will be made to <code>sumRegion</code>.</li> </ul>

Constructor Summary

Constructors

Constructor	Description
NumMatrix(int[][] matrix)

Method Summary

Modifier and Type	Method	Description
int	sumRegion(int row1, int col1, int row2, int col2)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

NumMatrix

public NumMatrix(int[][] matrix)

Method Details

sumRegion

public int sumRegion(int row1,
 int col1,
 int row2,
 int col2)