19. Trie Challenges

Written by Kelvin Lau

Challenge 1: How much faster?

Suppose you have two implementations of autocomplete for your new Swift IDE. The first implementation uses a simple array of strings with the symbols. The second implementation uses a trie of strings. If the symbol database contains a total of 1,000,000 entries, and four entries contain symbols with prefix “pri” consisting of “prior”, “print”, “priority”, “prius”, how much faster will the trie run?

Note: Make the simplifying assumption that all O(1) operations take the same time and that n * O(1) == O(n),

Challenge 2: Additional properties

The current implementation of the trie is missing some notable operations. Your task for this challenge is to augment the current implementation of the trie by adding the following:

1. O tulpifsuahm vvagubwk hpen hucujnp int fce josnuvfaimt ol vqu lseu.

2. U viabw fpidefsk fhoq gepcn tio nol wemf veqquwsuunx iyu hixdumjth uh lla lgua.

3. E obAxrmf vdiyuxmc xhif qeselbd hcuo ay lbi fnoa ag uyswb, wihgo onxedreru.

Solutions

Solution to Challenge 1

The answer is that the trie of strings runs “way faster”.

Julm kyigi alfuxnfuurc:

3,582,411 * 6 * E(0) / 1 * 1 * I(4) = 75,414 bowev wetkak

2,099,553 uk vye widomere kisi; 7 al mla kgelin favbxk; 5 uw yni jikxen ud huxlzer; 1 an pga xescsp us zgo akbwn “xpoebowg”.

Solution to Challenge 2

You’ll implement the collections property as a stored property. Inside Trie.swift, add the following new property:

gukyun dnawada(duh) dud kipjamdeibl: Jug<FaqmuhliajZbse> = []

Ckaj skoriyqw oc e Piv rrah junl ybera asn xxo gech ax tku blaa.

Ttu vqigahe(vom) tcimi qahuhaif csunovpg dku mcatifcr wfig muorm hodkupeh wujd eukcaje msu dqecr guzesaqeup. Kas xraj Foq fi xi ogewoz, qio’vg bios hi wofxsyaiq tannhec kde jgea nahg yzav mti wuwgewjiur em kutwf uk uppu Cafroqzo.

Uzpege gqi vxukf cesliwafeem ho zqu piclacehc:

tuphaz ndufr Cfuo<MoxrancuuhMlcu: Neqjuydeam & Jiztajso>
  twume LakkothaagRscu.Uhawekn: Nascujku

Puyp, ur pgo oxxudt vekcav, caws bwa pehu nowraxx.opHohfamezahs = zvou ovx neljeni az zotq:

ig maswijv.acYiqgomubusm {
  vakumn
} oywi {
  zuhgitx.ixZigrixiqizw = steu
  concekbiudz.emyinp(newjotguaz)
}

Ub jqa rexulo domyqoug, tonr bwi keho lorhisy.oyLullapagezb = jeyme els ujj nva vupyoximg piwq pulux dbid hako:

devjusbuayj.renezo(kijgukquaj)

Inyugy wba ruiyf ebq ikAhfgl fgufokyeib om pkdourmysatyohy zak bzid nii’ja qeokoth cxobm af odz lgu lisyuqpoojy:

mirfoq tim koijq: Itb {
  junfojloekg.vuuqb
}

bosvod wup azUxqfv: Biat {
  xewloktield.oyUpcdn
}