Iteration and counts

Questions 1 to 5 of 8

1. 1. Which statement about the order in which a dict loop visits its keys is correct?

   Keys always come out sorted, for both int and str keysThe order depends on the hash of each key, so it can change from one run to the nextThe order depends only on the length of each key, so it never changesKeys come out in the order they were first added, and deleting a key and adding it back moves it to the end
2. 2. A for loop walks over scores and calls del scores[name] inside the loop. What happens?

   It raises RuntimeError: dictionary changed size during iteration on the next step of the loop, even when the deleted key was the last oneIt works, and the loop just skips the deleted keyIt works, but only when the deleted key is the last one the loop reachedIt raises KeyError on the first del, because the loop holds a copy of the dict
3. 3. A counted dict (a multiset) holds {3: 2, 5: 3, 9: 1}. How many items does the bag hold in total, and what does len(bag) return?

   3 items, and len(bag) returns 66 items, and len(bag) returns 66 items, and len(bag) returns 310 items, and len(bag) returns 3
4. 4. Which statement about changing a value inside a for k in bag: loop is correct?

   It raises RuntimeError, because any write to the dict counts as a change during iterationIt is safe, because assigning to an existing key does not change the dict's size
5. 5. bag[x] = bag[x] + 1 is safe when x is not yet a key, because the dict treats a missing value as 0.

   False, because bag[x] raises KeyError for a key that is not in the dictTrue, because the dict treats a missing value as 0