Question

Write an algorithm that finds the \(m\) smallest numbers in a list of \(n\) numbers.

Short answer

To find the \(m\) smallest numbers in a list of \(n\) numbers, initialize a list with the first \(m\) numbers, then for each remaining number, if it is smaller than the largest number in your list, replace that number with the current one. Repeat this until you've gone through all the numbers in the list.

Step-by-step solution

Initialize placeholders

Start by initializing a placeholder for the smallest numbers. This will be a list of size \(m\). Initially, you can fill it with the first \(m\) elements of the list.

Scan the list

Now scan through the list starting from index \(m\). For each element, compare it with the largest element in your smallest numbers list (which can be efficiently found if we keep the list sorted or use a max heap data structure).

Update placeholders

If the current element is smaller than the largest element in your 'smallest numbers' list, replace that largest element with the current one. Make sure to keep the 'smallest numbers' list sorted or the heap property maintained after this operation.

Iterate through the list

Repeat Step 3 for all elements in the list. At the end, your 'smallest numbers' list or min heap will contain the \(m\) smallest elements of the original list.