exercism 50-55

Author: kumar91gopi

README.md

@@ -268,6 +268,11 @@ solution of many challenges of [Leetcode](https://leetcode.com/), [Exercism](htt
 48. [Flatten Array](https://github.com/kumar91gopi/Algorithms-and-Data-Structures-in-Ruby/blob/master/exercism/flatten_array.rb)
 49. [Phone Number](https://github.com/kumar91gopi/Algorithms-and-Data-Structures-in-Ruby/blob/master/exercism/phone_number.rb)
 50. [Grains](https://github.com/kumar91gopi/Algorithms-and-Data-Structures-in-Ruby/blob/master/exercism/grains.rb)
+51. [Resistor Color Trio](https://github.com/kumar91gopi/Algorithms-and-Data-Structures-in-Ruby/blob/master/exercism/resistor_color_trio.rb)
+52. [Saddle Points](https://github.com/kumar91gopi/Algorithms-and-Data-Structures-in-Ruby/blob/master/exercism/saddle_points.rb)
+53. [ETL](https://github.com/kumar91gopi/Algorithms-and-Data-Structures-in-Ruby/blob/master/exercism/etl.rb)
+54. [Nucleotide Count](https://github.com/kumar91gopi/Algorithms-and-Data-Structures-in-Ruby/blob/master/exercism/nucleotide_count.rb)
+55. [Pythogorean Triplet](https://github.com/kumar91gopi/Algorithms-and-Data-Structures-in-Ruby/blob/master/exercism/pythogorean_triplet.rb)
 
 <a name="leetcode"/>
 

exercism/etl.rb

@@ -0,0 +1,14 @@
+#Problem: https://exercism.org/tracks/ruby/exercises/etl
+
+#Solution
+class ETL
+    def self.transform(old_mapping)
+      new_mapping = {}
+      old_mapping.each do |point,letters|
+        letters.each do |letter|
+          new_mapping[letter.downcase]=point
+        end
+      end
+      new_mapping
+    end
+end

exercism/nucleotide_count.rb

@@ -0,0 +1,25 @@
+#Problem: https://exercism.org/tracks/ruby/exercises/nucleotide-count
+
+#Solution
+class Nucleotide
+    def initialize(dna_strand)
+      nucleotides = dna_strand.split("")
+      @nucleotide_count = { 'A' => 0, 'T' => 0, 'C' => 0, 'G' => 0 }
+      nucleotides.each do |nucleotide|
+        raise ArgumentError unless @nucleotide_count.has_key?(nucleotide)
+        @nucleotide_count[nucleotide]+=1
+      end
+    end
+    
+    def self.from_dna(dna_strand)
+      Nucleotide.new(dna_strand)
+    end
+    
+    def count(nucleotide)
+      @nucleotide_count[nucleotide]
+    end
+    
+    def histogram
+      @nucleotide_count
+    end
+end

exercism/pythogorean_triplet.rb

@@ -0,0 +1,28 @@
+#Problem: https://exercism.org/tracks/ruby/exercises/pythagorean-triplet
+
+#Solution
+class PythagoreanTriplet
+    def self.triplets_with_sum(n)
+      triplets = []
+      for b in 4..(n-1)
+        deno = 2*(n-b)
+        n_sq = n**2
+        a = (n_sq-(2*n*b))/deno
+        c = (n_sq/deno)-b
+        triplets.push([a,b,c]) if a>0 and a<b and c>b and a+b+c==n
+      end
+      triplets = triplets.sort_by{|val| val[0]}   
+    end
+end
+  
+#Solution 2
+class PythagoreanTriplet
+    def self.triplets_with_sum(sum)
+      (1..sum / 3).each_with_object([]) do |side_a, triplets|
+        side_b = (sum * (sum - 2 * side_a)) / (2 * (sum - side_a))
+        side_c = sum - side_a - side_b
+        next if side_b < side_a || side_c < side_b
+        triplets << [side_a, side_b, side_c] if (side_a**2 + side_b**2 == side_c**2)
+      end
+    end
+end

exercism/resistor_color_trio.rb

@@ -0,0 +1,30 @@
+#Problem : https://exercism.org/tracks/ruby/exercises/resistor-color-trio
+
+#Solution
+class ResistorColorTrio
+    COLOR_CODES = {
+                    "black" => 0,
+                    "brown" => 1,
+                    "red" => 2,
+                    "orange" => 3,
+                    "yellow" => 4,
+                    "green" => 5,
+                    "blue" => 6,
+                    "violet" => 7,
+                    "grey" => 8,
+                    "white" => 9
+                  }
+    def initialize(colors)
+      @color_bands = colors
+    end
+    
+    def label
+      resistor_val = (COLOR_CODES[@color_bands[0]]*10 + COLOR_CODES[@color_bands[1]])*(10**COLOR_CODES[@color_bands[2]])
+      unit = "ohms"
+      if resistor_val>1000
+        resistor_val/=1000
+        unit = "kiloohms"
+      end
+      "Resistor value: #{resistor_val} #{unit}"
+    end
+  end

exercism/saddle_points.rb

@@ -0,0 +1,38 @@
+#Problem: https://exercism.org/tracks/ruby/exercises/saddle-points
+
+#Solution
+class Grid
+    def self.saddle_points(input)
+      row_min_map = self.get_row_min_map(input)
+      col_min_map = self.get_col_min_map(input)
+      saddle_points = []
+      input.each_with_index do |row,row_index|
+        row.each_with_index do |element,col_index|
+          if element>=row_min_map[row_index+1] && element<=col_min_map[col_index+1]
+            saddle_points.append({"row"=>row_index+1,"column"=>col_index+1}) 
+          end
+        end
+      end   
+      return saddle_points
+    end
+    
+    def self.get_row_min_map(input)
+      row_min_map={}
+      input.each_with_index do |row,index|
+        row_min_map[index+1] = row.max
+      end
+      row_min_map
+    end
+
+    def self.get_col_min_map(input)
+      col_min_map={}
+      for i in (0...input[0].length) do
+        min = input[0][i]
+        for j in (0...input.length) do
+          min = input[j][i] if min>=input[j][i]
+        end
+        col_min_map[i+1]=min
+      end
+      col_min_map
+    end   
+end