Commit b2d23cd

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+<<-DOC
+You have a list of dishes. 
+Each dish is associated with a list of ingredients used to prepare it.
+You want to group the dishes by ingredients, 
+so that for each ingredient you'll be able to find all the dishes that contain it
+(if there are at least 2 such dishes).
+
+Return an array where each element is a list with the first element equal to the name of the
+ingredient and all of the other elements equal to the names of dishes that contain this ingredient.
+The dishes inside each list should be sorted lexicographically.
+The result array should be sorted lexicographically by the names of the ingredients in its elements.
+
+Example
+
+For
+  dishes = [["Salad", "Tomato", "Cucumber", "Salad", "Sauce"],
+            ["Pizza", "Tomato", "Sausage", "Sauce", "Dough"],
+            ["Quesadilla", "Chicken", "Cheese", "Sauce"],
+            ["Sandwich", "Salad", "Bread", "Tomato", "Cheese"]]
+the output should be
+  groupingDishes(dishes) = [["Cheese", "Quesadilla", "Sandwich"],
+                            ["Salad", "Salad", "Sandwich"],
+                            ["Sauce", "Pizza", "Quesadilla", "Salad"],
+                            ["Tomato", "Pizza", "Salad", "Sandwich"]]
+For
+  dishes = [["Pasta", "Tomato Sauce", "Onions", "Garlic"],
+            ["Chicken Curry", "Chicken", "Curry Sauce"],
+            ["Fried Rice", "Rice", "Onions", "Nuts"],
+            ["Salad", "Spinach", "Nuts"],
+            ["Sandwich", "Cheese", "Bread"],
+            ["Quesadilla", "Chicken", "Cheese"]]
+the output should be
+  groupingDishes(dishes) = [["Cheese", "Quesadilla", "Sandwich"],
+                            ["Chicken", "Chicken Curry", "Quesadilla"],
+                            ["Nuts", "Fried Rice", "Salad"],
+                            ["Onions", "Fried Rice", "Pasta"]]
+Input/Output
+
+[time limit] 4000ms (rb)
+[input] array.array.string dishes
+
+An array of dishes. 
+dishes[i] for each valid i contains information about the ith dish: the first element of dishes[i] is the name of the dish and the following elements are the ingredients of that dish.
+Both the dish name and the ingredient names consist of English letters and spaces.
+It is guaranteed that all dish names are different.
+It is also guaranteed that ingredient names for one dish are also pairwise different.
+
+Guaranteed constraints:
+1 ≤ dishes.length ≤ 500,
+2 ≤ dishes[i].length ≤ 10,
+1 ≤ dishes[i][j].length ≤ 50.
+
+[output] array.array.string
+
+The array containing the grouped dishes.
+DOC
+
+describe "#grouping_dishes" do
+  def grouping_dishes(dishes)
+    []
+  end
+
+  [
+    { dishes: [["Salad","Tomato","Cucumber","Salad","Sauce"], ["Pizza","Tomato","Sausage","Sauce","Dough"], ["Quesadilla","Chicken","Cheese","Sauce"], ["Sandwich","Salad","Bread","Tomato","Cheese"]], x: [["Cheese","Quesadilla","Sandwich"], ["Salad","Salad","Sandwich"], ["Sauce","Pizza","Quesadilla","Salad"], ["Tomato","Pizza","Salad","Sandwich"]] },
+    { dishes: [["Pasta","Tomato Sauce","Onions","Garlic"], ["Chicken Curry","Chicken","Curry Sauce"], ["Fried Rice","Rice","Onions","Nuts"], ["Salad","Spinach","Nuts"], ["Sandwich","Cheese","Bread"], ["Quesadilla","Chicken","Cheese"]], x: [["Cheese","Quesadilla","Sandwich"], ["Chicken","Chicken Curry","Quesadilla"], ["Nuts","Fried Rice","Salad"], ["Onions","Fried Rice","Pasta"]] },
+    { dishes: [["Pasta","Tomato Sauce","Onions","Garlic"], ["Chicken Curry","Chicken","Curry Sauce"], ["Fried Rice","Rice","Onion","Nuts"], ["Salad","Spinach","Nut"], ["Sandwich","Cheese","Bread"], ["Quesadilla","Chickens","Cheeseeee"]], x: [] },
+    { dishes: [["First","a","b","c","d","e","f","g","h","i"], ["Second","i","h","g","f","e","x","c","b","a"]], x: [["a","First","Second"], ["b","First","Second"], ["c","First","Second"], ["e","First","Second"], ["f","First","Second"], ["g","First","Second"], ["h","First","Second"], ["i","First","Second"]] },
+  ].each do |x|
+    it do
+      result = grouping_dishes(x[:dishes])
+      expect(result).to match_array(x[:x])
+    end
+  end
+end