Question

I have a

List<string>

with 1500 strings. I am now using the following code to pull out only string that start with the string prefixText.

foreach(string a in <MYLIST>)
{            
    if(a.StartsWith(prefixText, true, null))
    {
        newlist.Add(a);                   
    }            
}

This is pretty fast, but I’m looking for google fast. Now my question is if I arrange the List in alphabetical order, then compare char by char can I make this faster? Or any other suggestions on making this faster?

Answer 1

1500 is usually too few:

• you could search it in parallel with a simple divide and conquer of the problem. Search each half of the list in two (or divide into three, four, …, parts) different jobs/threads.

• Or store the strings in a (not binary) tree instead. Will be O(log n).

• sorted in alphabetical order you can do a binary search (sort of the same as the previous one)