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 java.lang.Object
304 - Range Sum Query 2D - Immutable.

Medium

Given a 2D matrix matrix, handle multiple queries of the following type:

  • Calculate the sum of the elements of matrix inside the rectangle defined by its upper left corner (row1, col1) and lower right corner (row2, col2).

Implement the NumMatrix class:

  • NumMatrix(int[][] matrix) Initializes the object with the integer matrix matrix.
  • int sumRegion(int row1, int col1, int row2, int col2) Returns the sum of the elements of matrix inside the rectangle defined by its upper left corner (row1, col1) and lower right corner (row2, col2).

Example 1:

Input

 ["NumMatrix", "sumRegion", "sumRegion", "sumRegion"]
 [[[[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]]

Output: [null, 8, 11, 12]

Explanation:

 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)

Constraints:

  • m == matrix.length
  • n == matrix[i].length
  • 1 <= m, n <= 200
  • -105 <= matrix[i][j] <= 105
  • 0 <= row1 <= row2 < m
  • 0 <= col1 <= col2 < n
  • At most 104 calls will be made to sumRegion.

  • 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)