Problem

Given a list of integers, return a dictionary where the key is the integer and the value is the number of times the integer appears in the list.
Example input: [1, 2, 1, 2, 1, 3, 3, 3, 4, 4, 4, 4]
Example output: {1: 3, 2: 2, 3: 3, 4: 4}

Solution

def count_list(lst):
    
    This function takes a list of integers and returns a dictionary where the key is the integer and the value is the number of times the integer appears in the list.
    
    # create an empty dictionary
    d = {}
    # loop through the list
    for i in lst:
        # if the integer is not in the dictionary, add it as a key and set the value to 1
        if i not in d:
            d[i] = 1
        # if the integer is in the dictionary, increment the value by 1
        else:
            d[i] += 1
    # return the dictionary
    return d

# test the function
print(count_list([1, 2, 1, 2, 1, 3, 3, 3, 4, 4, 4, 4]))