Moving Top Disc Tower Of Hanoi Using Recursion Java -
i have weird issue whenever program attempts solve tower of hanoi puzzle. whenever tries solve it, move first 2 discs on end pole (the pole way right), move remainder of discs starting pole. example, if have tower of hanoi 10 discs, move first several discs start pole, top 2 make end pole. rest of discs end on first pole. when this, gives me index out of bounds error. not sure going wrong it, , appreciated. in advance.
public class towerofhanoi { private int[] towerone; private int[] towertwo; private int[] towerthree; private int discone; private int disctwo; private int discthree; /* construct towers of hanoi (3 towers) anumdisc * on first tower. each tower can identified * integer number (0 first tower, 1 second * tower, , 2 third tower). each disc can identified * integer number starting 0 (for smallest disc) * , (anumdisc - 1) largest disc. */ public towerofhanoi(int anumdiscs) { towerone = new int[anumdiscs]; for(int = 0; < anumdiscs; i++){ towerone[i] = anumdiscs - 1 - i; } towertwo = new int[anumdiscs]; towertwo[0] = anumdiscs; towerthree = new int[anumdiscs]; towerthree[0] = anumdiscs; discone = anumdiscs; disctwo = 0; discthree = 0; } /* returns array of integer representing order of * discs on tower (from bottom up). bottom disc should * first element in array , top disc should * last element of array. size of array must * number of discs on tower. example, suppose * tower 0 contains following discs 0,1,4,6,7,8 (from top * bottom). method should return array [8,7,6,4,1,0] * (from first last). * @param tower integer identify tower number. * @return array of integer representing order of discs. */ public int[] getarrayofdiscs(int tower) { int[] temptower; if(tower == 0){ temptower = new int[discone]; for(int = 0; < discone; i++){ temptower[i] = towerone[i]; } return temptower; } if(tower == 1){ temptower = new int[disctwo]; for(int = 0; < disctwo; i++){ temptower[i] = towertwo[i]; } return temptower; } if(tower == 2){ temptower = new int[discthree]; for(int = 0; < discthree; i++){ temptower[i] = towerthree[i]; } return temptower; } return towerone; } /* gets total number of discs in towers of hanoi * @return total number of discs in towers of hanoi */ public int getnumberofdiscs() { return discone+disctwo+discthree; } /* gets number of discs on tower. * @param tower tower identifier (0, 1, or 2) * @return number of discs on tower. */ public int getnumberofdiscs(int tower) { if(tower == 0){ return discone; } if(tower == 1){ return disctwo; } if(tower == 2){ return discthree; } return 0; } /* moves top disc fromtower totower. note * operation has follow rule of tower of hanoi * puzzle. first fromtower must have @ least 1 disc , second * top disc of totower must not smaller top disc * of fromtower. * @param fromtower source tower * @param totower destination tower * @return true if move top disc * fromtower totower. */ public boolean movetopdisc(int fromtower, int totower) { if((fromtower == 0 && discone == 0)||(fromtower == 1 && disctwo == 0) || (fromtower == 2 && discthree == 0)){ return false; } if(fromtower == 0){ if(totower == 1){ if(disctwo != 0&&towerone[discone-1]>towertwo[disctwo-1]){ return false; } else{ towertwo[disctwo]=towerone[discone-1]; towerone[discone-1] = 0; discone--; disctwo++; return true; } } if(totower == 2){ if(discthree != 0&&towerone[discone-1] > towerthree[discthree-1]){ return false; } else{ towerthree[discthree] = towerone[discone-1]; towerone[discone-1] = 0; discone--; discthree++; return true; } } } if(fromtower == 1){ if(totower == 0){ if(discone != 0&&towertwo[disctwo-1]>towerone[discone-1]){ return false; } else{ towerone[discone]=towertwo[disctwo-1]; towertwo[disctwo-1] = 0; disctwo--; discone++; return true; } } if(totower == 2){ if(discthree!= 0&&towertwo[disctwo-1] > towerthree[discthree-1]){ return false; } else{ towerthree[discthree] = towertwo[disctwo-1]; towertwo[disctwo-1] = 0; disctwo--; discthree++; return true; } } } if(fromtower == 2){ if(totower == 0){ if(discone !=0 && towerone[discone-1]>towertwo[disctwo-1]){ return false; } else{ towerone[discone]=towerthree[discthree-1]; towerthree[discthree-1] = 0; discthree--; discone++; return true; } } if(totower == 1){ if(discthree !=0&&towerthree[discthree-1] > towertwo[disctwo-1]){ return false; } else{ towertwo[disctwo] = towerthree[discthree-1]; towerthree[discthree-1] = 0; discthree--; disctwo++; return true; } } } return false; } } this class using run program above.
import javax.swing.jframe; public class thsolverframe { public static void main(string[] args) throws interruptedexception { int numberofdiscs = 10; towerofhanoi towers = new towerofhanoi(numberofdiscs); thcomponent thc = new thcomponent(towers); jframe frame = new jframe(); frame.settitle("tower of hanoi"); frame.setsize(500,500); frame.setdefaultcloseoperation(jframe.exit_on_close); frame.add(thc); frame.setvisible(true); thread.sleep(5000); solvetower(towers, thc, numberofdiscs, 0, 1, 2); system.out.println("done!!!"); } public static void solvetower(towerofhanoi towers, thcomponent thc, int numberofdiscs, int startpole, int temppole, int endpole) throws interruptedexception { if(numberofdiscs == 1) { towers.movetopdisc(startpole, endpole); thc.repaint(); thread.sleep(100); } else { solvetower(towers, thc, numberofdiscs - 1, startpole, endpole, temppole); towers.movetopdisc(startpole, endpole); thc.repaint(); thread.sleep(100); solvetower(towers, thc, numberofdiscs - 1, temppole, startpole, endpole); } } }
i tracked down 2 lines in movetopdisk() method. first 1 this:
if(fromtower == 2){ if(totower == 0){ if(discone !=0 && towerone[discone-1]>towertwo[disctwo-1]){ <---- here the third if statement here trying access towertwo when should using towerthree , discthree changed this:
if (fromtower == 2) { if (totower == 0) { if (discone != 0 && towerone[discone - 1] > towerthree[discthree - 1]) { the way before, code trying pull disc tower without discs on , causing error. after running again, found such typo within same area. :
if(totower == 1){ if(discthree !=0&&towerthree[discthree-1] > towertwo[disctwo-1]){ this second if statement targeting discthree, when should using disctwo.
if(totower == 1){ if(disctwo !=0&&towerthree[discthree-1] > towertwo[disctwo-1]){ after these changes, code ran me, error free. issue had after unable solve puzzle! algorithm not able solve puzzle above 3 discs. tried 3, 4, 5, , 10 , solved 3. 4 , 5, program stopped, not in winning configuration , when tried 10, managed shuffle first 3 discs around , never come solution (i let run solid 5 minutes in case).
tl;dr suggestions careful of copy/pasting, mindful of whether using zero-index or not, , should take @ algorithm again see if can solve puzzle. myself have not written hanoi puzzle, i'm not familiar how implement in code. see have idea though. being solve puzzle n discs, first have solve n-1 discs. luck on rest of work!
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