hotel comprehension

we have information about a hotel. The hotel has stored its information in a Python list. The list contains lists (representing rooms), and each sublist contains one or more dictionaries (representing people).

here’s the data structure

### useful data about hotel
rooms = [[{'age': 14, 'hobby': 'horses', 'name': 'Avram'},  
          {'age': 12, 'hobby': 'piano', 'name': 'Betty'},  
          {'age': 9, 'hobby': 'chess', 'name': 'Chen'},  
          {'age': 15, 'hobby': 'programming', 'name': 'Dov'}],
         [{'age': 17, 'hobby': 'driving', 'name': 'Efrat'}],  
         [{'age': 45, 'hobby': 'writing', 'name': 'Fred'},  
          {'age': 43, 'hobby': 'chess', 'name': 'Greg'},
          {'age': 20, 'hobby': 'surfing', 'name': 'Hofit'}]
          ]

1. What are the names of the people staying at our hotel?

2. What are the names of people staying in our hotel who enjoy chess?

3. what unique hobbies are enjoyed in rooms with at least 2 people?

group by length of word

given a list of words

words = ['everything', 'should', 'be', 'as', 'simple', 'as', 'possible',
         'but', 'no', 'simpler', 'albert', 'einstein'
        ]

creat a nested list of words, grouped by the length of the words

grouped_by_len = [
     [],
     ['be', 'as', 'as', 'no'],
     ['but'],
     [],
     [],
     ['should', 'simple', 'albert'],
     ['simpler'],
     ['possible', 'einstein'],
     [],
     ['everything']
    ]

tranform a nested list

given a nested list of numbers

nums = [
 [-3],
 [-2, -1],
 [0, 1, 2],
 [3, 4, 5, 6],
 [7, 8, 9, 10, 11]
 ]

transform it into a list of the cumulative sums

cumsum = [
 [-3],
 [-2, -3],
 [0, 1, 3],
 [3, 7, 12, 18],
 [7, 15, 24, 34, 45]
 ]

hint: you may use this code to calculate a cumulative sum for a list:

def cumsum(lst_):
    total = 0
    for val in lst:
        total += val
        yield total