bcb-0004
1.000
Proposed solution
```python
from collections import Counter
import itertools
def task_func(d):
"""
Count the occurrence of each integer in the values of the input dictionary, where each value is a list of integers,
and return a dictionary with these counts. The resulting dictionary's keys are the integers, and the values are
their respective counts across all lists in the input dictionary.
Parameters:
d (dict): A dictionary where each key is a string and the value is a list of integers.
Returns:
dict: A dictionary where each key is an integer from any of the input lists, and the value is the count of
how often that integer appears in all the lists combined.
Requirements:
- collections.Counter
- itertools
Example:
>>> d = {'a': [1, 2, 3, 1], 'b': [3, 4, 5], 'c': [1, 2]}
>>> count_dict = task_func(d)
>>> print(count_dict)
{1: 3, 2: 2, 3: 2, 4: 1, 5: 1}
"""
# Flatten all lists from the dictionary values
flattened_list = list(itertools.chain.from_iterable(d.values()))
# Count occurrences of each integer
count_dict = dict(Counter(flattened_list))
return count_dict
```Test output (stdout)
........ [100%] 8 passed in 0.02s
System prompt
You are an expert programmer. Solve the task exactly as specified. Output your solution as fenced code blocks using the required file name(s) and the exact function/type signatures requested. Prefer correctness; do not include prose outside code unless asked.