Daniela - matrix check sum

lib/matrix_check_sum.rb

@@ -2,6 +2,37 @@
 # whether the sum of each row matches the sum of corresponding column i.e. sum
 # of numbers in row i is the same as the sum of numbers in column i for i = 0 to row.length-1
 # If this is the case, return true. Otherwise, return false.
+
+#time complexity O(n^2), space complexity O(1)
+
 def matrix_check_sum(matrix)
-  raise NotImplementedError
+  rows = matrix.size
+  columns = matrix[0].size
+
+  i = 0
+  until i == rows
+
+    rowsum = 0
+    col = 0
+    row = i
+    until col == columns  # sum row
+      rowsum += matrix[row][col]
+      col += 1
+    end
+
+    colsum = 0
+    row = 0
+    col = i
+    until row == rows  # sum column
+      colsum += matrix[row][col]
+      row += 1
+    end
+
+    return false if rowsum != colsum
+
+    i += 1
+
+  end
+
+return true
 end

specs/matrix_check_sum_spec.rb

@@ -1,5 +1,6 @@
 require 'minitest/autorun'
 require 'minitest/reporters'
+require 'minitest/skip_dsl'
 require_relative '../lib/matrix_check_sum'
 
 describe "matrix check sum" do