Sockets - Shubha

lib/matrix_convert_to_zero.rb

@@ -1,10 +1,54 @@
+require "pry"
 # Updates the input matrix based on the following rules:
 # Assumption/ Given: All numbers in the matrix are 0s or 1s
 # If any number is found to be 0, the method updates all the numbers in the
 # corresponding row as well as the corresponding column to be 0.
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O (m * n) where m and n are the dimensions of the array
+# Space complexity: O(1) because the first row and column of the matrix are used as buffer space. The only new variables created are i, j, first_row_zero, and first_column_zero
 def matrix_convert_to_zero(matrix)
-  raise NotImplementedError
+  i = 0
+  # Record locations of zeros
+  while i < matrix.length
+    j = 0
+    while j < matrix[i].length
+      if matrix[i][j] == 0
+        matrix[i][0] = 0
+        matrix[0][j] = 0
+        (first_row_zero = true) if (i == 0)
+        (first_column_zero = true) if (j == 0)
+      end
+      j += 1
+    end
+    i += 1
+  end
+
+  # Change inner rows + columns
+  i = 1
+  while i < matrix.length
+    j = 1
+    while j < matrix[i].length
+      if (matrix[i][0] == 0) || (matrix[0][j] == 0)
+        matrix[i][j] = 0
+      end
+      j += 1
+    end
+    i += 1
+  end
+
+  if first_row_zero
+    j = 0
+    while j < matrix[0].length
+      matrix[0][j] = 0
+      j += 1
+    end
+  end
+
+  if first_column_zero
+    i = 0
+    while i < matrix.length
+      matrix[i][0] = 0
+      i += 1
+    end
+  end
 end