Merge pull request #750 from fartem/304_Range_Sum_Query_2D-Immutable

2024-10-17 v. 6.8.3: added "304. Range Sum Query 2D - Immutable"

Author: fartem

README.md

@@ -548,3 +548,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 287. Find the Duplicate Number                                  | [Link](https://leetcode.com/problems/find-the-duplicate-number/)                                  | [Link](./lib/medium/287_find_the_duplicate_number.rb)                                  | [Link](./test/medium/test_287_find_the_duplicate_number.rb)                                  |
 | 299. Bulls and Cows                                             | [Link](https://leetcode.com/problems/bulls-and-cows/)                                             | [Link](./lib/medium/299_bulls_and_cows.rb)                                             | [Link](./test/medium/test_299_bulls_and_cows.rb)                                             |
 | 300. Longest Increasing Subsequence                             | [Link](https://leetcode.com/problems/longest-increasing-subsequence/)                             | [Link](./lib/medium/300_longest_increasing_subsequence.rb)                             | [Link](./test/medium/test_300_longest_increasing_subsequence.rb)                             |
+| 304. Range Sum Query 2D - Immutable                             | [Link](https://leetcode.com/problems/range-sum-query-2d-immutable/)                               | [Link](./lib/medium/304_range_sum_query_2d_immutable.rb)                               | [Link](./test/medium/test_304_range_sum_query_2d_immutable.rb)                               |

leetcode-ruby.gemspec

@@ -5,7 +5,7 @@ require 'English'
 ::Gem::Specification.new do |s|
   s.required_ruby_version = '>= 3.0'
   s.name = 'leetcode-ruby'
-  s.version = '6.8.2'
+  s.version = '6.8.3'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/medium/304_range_sum_query_2d_immutable.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/range-sum-query-2d-immutable/
+class NumMatrix
+  # @param {Integer[][]}
+  def initialize(matrix)
+    return if matrix.empty? || matrix.first.empty?
+
+    @dp = ::Array.new(matrix.size + 1) { ::Array.new(matrix[0].size + 1, 0) }
+    matrix.each_with_index do |row, r|
+      row.each_with_index do |val, c|
+        @dp[r + 1][c + 1] = @dp[r + 1][c] + @dp[r][c + 1] + val - @dp[r][c]
+      end
+    end
+  end
+
+  # @param {Integer} row1
+  # @param {Integer} col1
+  # @param {Integer} row2
+  # @param {Integer} col2
+  # @return {Integer}
+  def sum_region(row1, col1, row2, col2)
+    @dp[row2 + 1][col2 + 1] - @dp[row1][col2 + 1] - @dp[row2 + 1][col1] + @dp[row1][col1]
+  end
+end

test/medium/test_304_range_sum_query_2d_immutable.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/304_range_sum_query_2d_immutable'
+require 'minitest/autorun'
+
+class RangeSumQuery2DImmutableTest < ::Minitest::Test
+  def test_default_one
+    num_matrix = ::NumMatrix.new(
+      [
+        [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]
+      ]
+    )
+
+    assert_equal(8, num_matrix.sum_region(2, 1, 4, 3))
+    assert_equal(11, num_matrix.sum_region(1, 1, 2, 2))
+    assert_equal(12, num_matrix.sum_region(1, 2, 2, 4))
+  end
+end