Question

I have an array of items and I need to find the matching ones(duplicates). I have the simplest O(n^2) algorithm running for now. Item type doesn’t really matter, but if you want to know it’s image.

myarray;   
for(i = 0; i < myarray.length - 1; i++) 
    for(int j = i+1; j < myarray.length; j++) 
        if(myarray[i] = myarray[j]) 
           output(names of items);

I tried Wikipedia and Google, but couldn’t come out with an answer. Any links or algorithms or code in any language would be great.

Answer 1

Rather than sort and then compare adjacent items, why not add each item to a self balancing binary tree, thus you get the ‘already present’ check for free (sort of).