COMP 250 Ltur 29 rp trvrsl Nov. 15/16, 2017 1
Toy Rursv rp trvrsl pt rst Non-rursv rp trvrsl pt rst rt rst 2
Hs up! Tr wr w mstks n t sls or S. 001 or toy s ltur. So you r ollown t ltur rorns n usn ts (orrt) sls, tn you wll not som rns. 3
Rll: tr trvrsl (rursv) ptrst Tr (root){ (root s not mpty){ root.vst = tru // prorr or l o root ptrst Tr( l ) 4
Grp trvrsl (rursv) N to spy strtn vrtx. Vst ll nos tt r rl y pt rom strtn vrtx. 5
Grp trvrsl (rursv) ptfrst_grp(v){ v.vst = tru or w su tt (v,w) s n E // w n v.jlst? // Hr vstn just mns rn 6
Grp trvrsl (rursv) ptfrst_grp(v){ v.vst = tru or w su tt (v,w) s n E // w n v.jlst! (w.vst) // vos yls ptfrst_grp(w) // Hr vstn just mns rn 7
Cll Stk or ptfrst() ptfrst_grp(v){ v.vst = tru or w su tt (v,w) s n E! (w.vst) ptfrst_grp(w) 8
Cll Stk or ptfrst() ptfrst_grp(v){ v.vst = tru or w su tt (v,w) s n E! (w.vst) ptfrst_grp(w) 9
Cll Stk or ptfrst() ptfrst_grp(v){ v.vst = tru or w su tt (v,w) s n E! (w.vst) ptfrst_grp(w) 10
Cll Stk or ptfrst() ptfrst_grp(v){ v.vst = tru or w su tt (v,w) s n E! (w.vst) ptfrst_grp(w) 11
Cll Stk or ptfrst() ptfrst_grp(v){ v.vst = tru or w su tt (v,w) s n E! (w.vst) ptfrst_grp(w) 12
root Cll Tr 13
Exmpl 2 Wt s t ll tr or ptfrst( )? Ajny Lst - (,) - (,,) - (,) - (,,) - (,,,) - (,,) - (,) - (,,) - (,) 14
Exmpl 2 ll tr or ptfrst() 15
Q: Non-rursv rp trvrsl? A: Smlr to tr trvrsl: Us stk or quu. 16
Rll: pt rst tr trvrsl (wt slt vrton) trtrvrslusnstk(root){ ntlz mpty stk s vst root s.pus(root) wl s s not mpty { ur = s.pop() or l o ur{ vst l s.pus(l) Vst no or pusn t onto t stk. Evry no n t tr ts vst, pus, n tn popp. 17
Gnrlz to rps rptrvrslusnstk(v){ ntlz mpty stk s v.vst = tru s.pus(v) wl (!s.mpty) { u = s.pop() or w n u.jlst{ (!w.vst){ w.vst = tru s.pus(w) // t only nw prt 18
Exmpl: rptrvrslusnstk() 19
Exmpl: rptrvrslusnstk() T trvrsl ns tr, ut t s not ll tr. Wy not? s popp n ot n r pus. 20
Exmpl: rptrvrslusnstk() s popp n ot n r pus. 21
Exmpl: rptrvrslusnstk() s popp n s pus. 22
Exmpl: rptrvrslusnstk() s popp n s pus. 23
Exmpl: rptrvrslusnstk() s popp n s pus. 24
Exmpl: rptrvrslusnstk() s popp n s pus. 25
Exmpl: rptrvrslusnstk() Orr o nos vst: 26
Rll: rt rst tr trvrsl (s ltur 20) or lvl vst ll nos t lvl trtrvrslusnquu(root){ ntlz mpty quu q q.nquu(root) wl q s not mpty { ur = q.quu() vst ur or l o ur q.nquu(l) j k 27
Brt rst rp trvrsl Gvn n nput vrtx, n ll vrts tt n r y pts o lnt 1, 2, 3, 4,. 28
Brt rst rp trvrsl rptrvrslusnquu(v){ ntlz mpty quu q v.vst = tru q.nquu(v) wl (! q.mpty) { u = q.quu() or w n u.jlst{ (!w.vst){ w.vst = tru q.nquu(w) 29
Exmpl rptrvrslusnquu() quu 30
Exmpl rptrvrslusnquu() quu 31
Exmpl rptrvrslusnquu() quu Bot, r vst n nquu or s quu. 32
Exmpl rptrvrslusnquu() quu 33
rptrvrslusnquu() It ns tr wos root s t strtn vrtx. It ns t sortst pt (numr o vrts) to ll vrts rl rom strtn vrtx. 34
Exmpl: rptrvrslusnquu() 1 35
Exmpl: rptrvrslusnquu() 1 2 3 36
Exmpl: rptrvrslusnquu() 1 2 4 3 5 37
Exmpl: rptrvrslusnquu() 1 2 4 3 5 6 38
Exmpl: rptrvrslusnquu() 6 1 2 4 3 5 7 39
Exmpl: rptrvrslusnquu() 1 2 4 3 5 7 6 8 40
Exmpl: rptrvrslusnquu() 1 2 4 3 5 7 6 8 41
Exmpl: rptrvrslusnquu() 1 2 4 3 5 7 6 8 9 42
Exmpl: rptrvrslusnquu() 1 2 4 3 5 7 6 8 9 43
Exmpl: rptrvrslusnquu() T trvrsl ns tr, ut t s not ll tr. Wy not? 44
Rll: How to mplmnt Grp lss n Jv? lss Grp<T> { HsMp< Strn, Vrtx<T> > vrtxmp; lss Vrtx<T> { ArryLst<E> T ooln jlst; lmnt; vst; lss E { Vrtx oul : nvrtx; wt;
HEADS UP! Pror to trvrsl,. or w n V w.vst = ls How to mplmnt ts? 46
HEADS UP! Pror to trvrsl,. or w n V w.vst = ls How to mplmnt ts? lss Grp<T> { HsMp< Strn, Vrtx<T> > : pul vo rstvst() { vrtxmp; 47
HEADS UP! Pror to trvrsl,. or w n V w.vst = ls How to mplmnt ts? lss Grp<T> { HsMp< Strn, Vrtx<T> > vrtxmp; : pul vo rstvst() { or( Vrtx<T> v : vrtxmp.vlus() ){ v.vst = ls; [ASIDE: I somtn unnssrly omplt on t S.001 sls. Wt I v ov s ttr. ] 48