Medium data structure and algorithm practice puzzle.
Given two lists of words, return their bag-of-words cosine similarity, rounded to 3 decimals. Count each word in each list. Then take the dot product of the two count maps, and divide by the length of each one. Word order gets thrown away completely, so "dog bites man" and "man bites dog" score as identical.
Solve it three ways: snap the jigsaw pieces together, fill in the blanks, or type it from scratch against the tests. This one is free.
Every line of the solution comes with a note explaining why it is there, and a step by step replay shows the code running. At level 3, where you type it yourself, you can ask for an AI mock interview on this problem that ends with a hiring manager's scorecard.
Then grow it into a real project with the Software Engineer button: this puzzle becomes the Trip Fuzzy Matcher, a pipeline you can run and download. See every Software Engineer project.
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