ChuongVI Partten Searching Algorithm

7/23/2019 ChuongVI Partten Searching Algorithm

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Mt s khi nim v nh ngha c bn v tm kim mu:

Gi sAlphabet ltp hp (hoc tpcon ) cc m ASSCI.Mt tw =(w0, w1,..,wl)cdi l, w

l=nullging nh biu din cangnngC. Khitanh ngha mt

s thut ngsau:

Prefix(tin t).Tuc giltin t ca twnu tn ti mt tvw =uv( vcthlrng). Vd: u=AB ltin t ca w=ABCDEF v u=com ltin t caw=communication.

Suffix(hu t).Tvc gilhu t ca twnu tn ti mt t uw =uv

( ucthlrng). Vd: v=EF lhu t ca w=ABCDEF v v =tion lhu t caw =communication.

Factor(substring, subword).Mt t zc gilmtxu con,tcon haynhnt ca t wnu tn tihait u, v( u, v cth rng)sao cho w= uzv. Vd t z =CD l factorca t w=ABCDEF v z =muni l factorca w=communication.

Period(on).Mt s tnhin pc gilon ca t wnu vi mii(0


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6.3. Thutton Knuth-Morris-Prattc im:

Thc hin ttri sangphi. C phatin xlvi phc tpO(m). phc tp thutton l O(n + m);

Thutton PreKmp: //thc hin bc tin xlInput:

XumuX =(x0, x1,..,xm),di m.Output: MnggitrkmpNext[].Formats:

PreKmp(X, m, kmpNext);Actions :

i = 1; kmpNext[0] = 0; len = 0; //kmpNex[0] lun l 0while (i < m) {

if (X[i] == X[len] ) { //NuX[i] = X[len]len++; kmpNext[i] = len; i++;

}else { //NuX[i] != X[len]

if ( len != 0 ) { len = kmpNext[len-1]; }else { kmpNext[i] = 0; i++; }

}}

EndActions.


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6.7. Cy hu t

Cy hu t:Mtcyhu t ca vn bnX l cycnn chott ccchu tcaX. VdX = {bear, bell, bid, bull, buy, sell, stock, stop}. Khicyhu tbanu caXc gil cyhu t chun nh di ysau:


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ChuongVI Partten Searching Algorithm

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