Intermediate · Dictionaries · 133 of 264
Word frequency
Count how often each word appears (ignore capital letters). Print the words from the most to the least common; equally common words in alphabetical order.
Input: one line of words. Output: one line per word: <word> <count>
Examples
Input
the cat and the hat
Output
the 2 and 1 cat 1 hat 1
Input
a A a
Output
a 3
Input
one two three
Output
one 1 three 1 two 1
One more test checks other inputs when you press Check.
Stuck? The idea behind dictionaries
A dictionary links keys to values, like words to meanings: ages["Ann"] = 12. Looking up a key is fast, however big it is.
.get(key, 0) gives a default when the key isn't there; looping over a dictionary gives its keys, .items() gives keys and values together.
counts = {}
for word in input().split():
counts[word] = counts.get(word, 0) + 1
for word, n in counts.items():
print(word, n)Watch for: Reading a key that isn't there stops the program with a KeyError: check with in, or use .get().