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2 cards from this section. Quick, good the night before a test.
What is the total number of valid sequences of 1's and -1's?
Think about how many places you can choose for the 1's.
Define a bad sequence in your own words.
Consider sequences with parentheses or ladder-like paths.
What is the formula for Catalan numbers?
Recall the conclusion at the end of our session.
True or False: Set A is defined to include all legitimate sequences with no restrictions.
Think about the restrictions we talked about.
Given n = 4, find all valid sequences of 1's and -1's, and verify using the Catalan number formula.
Write out the sequences; account for each by ensuring partial sums are valid.
If the first two positive indices yield a negative sum, demonstrate the reflection method with an example.
Ask yourself how you can visualize the switch in numbers.
4 more questions in this section. Enroll free to practise them all.
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