Valintasortaus

Valintasortaus, often translated as selection sort, is a simple comparison-based sorting algorithm. It works by repeatedly finding the minimum element from the unsorted part of a list and putting it at the beginning. This process is continued until the entire list is sorted.

The algorithm divides the input list into two parts: a sorted sublist and an unsorted sublist. Initially, the sorted sublist is empty, and the unsorted sublist comprises the entire input list. In each iteration, the algorithm finds the smallest element in the unsorted sublist and swaps it with the first element of the unsorted sublist. This effectively moves the smallest element from the unsorted sublist to the end of the sorted sublist. The boundary between the sorted and unsorted sublists then shifts one element to the right.

Valintasortaus has a time complexity of O(n^2) in all cases, meaning its performance degrades quadratically with the size of the input. This is because it requires nested loops: an outer loop to iterate through the unsorted portion and an inner loop to find the minimum element within that portion. Despite its inefficiency for large datasets, valintasortaus is easy to understand and implement, making it a good choice for educational purposes or for sorting small lists. It performs a minimal number of swaps, which can be advantageous in certain scenarios where write operations are expensive.