Get All the Products
Our next example is an algorithm that accepts an array of numbers and returns the product of every combination of two numbers.
For example, if we passed in the array, [1, 2, 3, 4, 5], the function returns:
| | [2, 3, 4, 5, 6, 8, 10, 12, 15, 20] |
This is because we first multiply the 1 by the 2, 3, 4, and 5. Then we multiply the 2 by the 3, 4, and 5. Next, we multiply the 3 by the 4 and the 5. And finally, we multiply the 4 by the 5.
Note something interesting: when we multiply, say, the 2 by the other numbers, we only have to multiply it by the numbers that are to the right of it. We don’t have to go back and multiply 2 by the 1, because that was already covered back when we multiplied by the 1 by the 2. So, each number only ...
Get A Common-Sense Guide to Data Structures and Algorithms, Second Edition, 2nd Edition now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
