explanation for towers of hanoi

[poopsy]

hi guys
cud some1 explain to me the towers of hanoi code, the source code is available evrywhr. i've been trying to understand it bt cant. can some1 plz help me
i hav even tried to "trace" it but i still dnt understand hw it works plzzzz help

void Towers(int numDisks, char Source, char Dest, char Temp)
    {
        if (numDisks == 1)
        {
          cout << "\tMove top disk from pole " << Source << " to pole " << Dest << endl;
        }
        else
        {
          Towers(numDisks - 1, Source, Temp, Dest);
          Towers(1, Source, Dest, Temp);
          Towers(numDisks - 1, Temp, Dest, Source);
        }
    }
 
 

[JosAH]

Suppose you have to move a tower of n disks from position 1 to position 3. The
problem is solved when you are able to move a tower of n-1 disks from position
1 to position 2; move the largest disk (disk number n) from position 1 to position
3 directly and then do the same with that tower of n-1 disks: move it from position
2 to position 3 (on top of that largest disk n).

Nothing needs to be done if n == 0.

kind regards,

Jos

[poopsy]

ok suppose i have 4 disks
when it 1st enter the function it goes to the else part, it comes to this part of code:

Towers(numDisks - 1, Source, Temp, Dest);

therefore numdisks-1= 3, source = position 1, temp= position 2, dest=position 3

wat happens then, does it continue to the next part of code which is :

Towers(1, Source, Dest, Temp);

but then numdisks is still not equal to 1!!

???

[JosAH]

That code you've shown us is not correct; use the following code instead:

void Towers(int numDisks, char Source, char Dest, char Temp)
    {
        if (numDisks > 0)
        {
          Towers(numDisks - 1, Source, Temp, Dest);
          cout << "\tMove top disk from pole " << Source << " to pole " << Dest << endl;
          Towers(numDisks - 1, Temp, Dest, Source);
        }
    }
 

kind regards,

Jos

[kaioshin00]

Here's a better explanation than I can give

[poopsy]

if i want to show the positions of numdisks in each position after each pass, i.e i want to store it in an array, i'll have to declare 3 arrays for each of the 3 different positions where must i store it ( i.e whr in the code) and shud i display it after each call of the functions towers..plz guide me

[Ganon11]

If you want to display the positions, you'll want to do it once, before the solution is called, and then once for every move that's made (which will eventually include the solution). You'll also have to decide how you want to store it. You could declare three arrays large enough to hold the max number of disks, and then populate them with the disk numbers - but, with an original pile size of N, you'll only ever fill N out of 3N array slots, leaving 2N slots wasted.

Basically, printing isn't going to be your problem. How you keep track of what disk is where, and how you'll update this information, will be troublesome.