With Perl, you can make initializing and clearing constant by using autovivication with arrays. Allocate the @A as an empty array. Setting any value will expand the array and set the other values to undef. This is O(N) but it is fast. Clearing is emptying out the entire array. It also has the advantage that the size of the array is the largest value used. Your data structure uses autovivication for the A array so it has the same performance but more overhead.

It is also important to realize the importance of the constants to running time. Preallocating the array pays O(U) cost in initialization but makes each operation more efficient. When inserting N items close to U, this can be significant.

In reply to Re: Data structure challenge by iburrell
in thread Data structure challenge by Abigail-II

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.