Tower Of Hanoi | Practice | GeeksforGeeks

The tower of Hanoi is a famous puzzle where we have three rods and N disks. The objective of the puzzle is to move the entire stack to another rod. You are given the number of discs N. Initially, these discs are in the rod 1. You need to print all the steps of discs movement so that all the discs reach the 3rd rod. Also, you need to find the total moves.
Note: The discs are arranged such that the top disc is numbered 1 and the bottom-most disc is numbered N. Also, all the discs have different sizes and a bigger disc cannot be put on the top of a smaller disc. Refer the provided link to get a better clarity about the puzzle.
Example 1:
Input:
N = 2
Output:
move disk 1 from rod 1 to rod 2
move disk 2 from rod 1 to rod 3
move disk 1 from rod 2 to rod 3
3
Explanation: For N=2 , steps will be
as follows in the example and total
3 steps will be taken.
Example 2:
Input:
N = 3
Output:
move disk 1 from rod 1 to rod 3
move disk 2 from rod 1 to rod 2
move disk 1 from rod 3 to rod 2
move disk 3 from rod 1 to rod 3
move disk 1 from rod 2 to rod 1
move disk 2 from rod 2 to rod 3
move disk 1 from rod 1 to rod 3
7
Explanation: For N=3 , steps will be
as follows in the example and total
7 steps will be taken.

Your Task:
You don't need to read input or print anything. You only need to complete the function toh() that takes following parameters: N (number of discs), from (The rod number from which we move the disc), to (The rod number to which we move the disc), aux (The rod that is used as an auxiliary rod) and prints the required moves inside function body (See the example for the format of the output) as well as return the count of total moves made. The total number of moves are printed by the driver code.
Please take care of the case of the letters.
Expected Time Complexity: O(2N).
Expected Auxiliary Space: O(N).
Constraints:
1 <= N <= 16
0
iscream2 weeks ago
 public long f(int n,Stack<Integer> fromRod,Stack<Integer> toRod,Stack<Integer> auxRod,int from,int to,int aux){       if(n ==1){           int disk = fromRod.pop();           System.out.println("move disk " + disk +" from rod " + from+" to rod " + to);           toRod.push(disk);           return 1;       }       return f(n-1,fromRod,auxRod,toRod,from,aux,to) + f(1,fromRod,toRod,auxRod,from,to,aux) + f(n-1,auxRod,toRod,fromRod,aux,to,from);   }      public long toh(int N, int from, int to, int aux) {       Stack<Integer> fromRod = new Stack<>();       for(int i=N;i>=1;i--){           fromRod.push(i);       }       Stack<Integer> toRod = new Stack<>();       Stack<Integer> auxRod = new Stack<>();       return f(N,fromRod,toRod,auxRod,from,to,aux);                 }
+1
dipanshusharma93132 weeks ago
// java solution
class Hanoi {    public long toh(int N, int from, int to, int aux) {       // Your code here       long count = 0;       if(N == 0){           return 0;       }              count += toh(N-1, from, aux, to);       System.out.println("move disk "+N+" from rod "+from+" to rod "+to);       count += toh(N-1, aux, to, from);              return ++count;   }}
+1
swapniltayal4222 weeks ago
    long long toh(int N, int from, int to, int aux) {       //Your code here       long long count = 0;              if (N == 0){           return 0;       }       if (N > 0){           count += toh(N-1, from, aux, to);                      cout<<"move disk "<<N<<" from rod "<<from<<" to rod "<<to<<endl;                      count += toh(N-1, aux, to, from);       }       return count + 1;   }
0
swapniltayal4222 weeks ago
long long toh(int N, int from, int to, int aux) {   //Your code here   long long count = 0;      if (N == 0){       return 0;   }   if (N > 0){       count += toh(N-1, from, aux, to);              cout<<"move disk "<<N<<" from rod "<<from<<" to "<<to<<endl;              count += toh(N-1, aux, to, from);   }   return count + 1;}
+2
msf_venom0032 weeks ago
Self notes :
Transferring every plate execpt for last one on aux using the to rod 
and then putting the last or the heaviest on to(destination)
and then transferring everything back to destination using the from as aux (simple)
long long toh(int N, int from, int to, int aux) {
       if(N==0) return 0;
      // cout <<"move disk "<<from<<" from rod "<<aux<<"\n";
       long long cnt =1; // 1 for the extra step between two calls
       cnt += toh(N-1,from,aux,to);
       cout <<"move disk "<<N<<" from rod "<<from<<" to rod "<<to<<"\n";
       cnt += toh(N-1,aux,to,from);
       return cnt;
    }
0
ansumanrath543 weeks ago
Java Code:-
class Hanoi {

    public long toh(int N, int from, int to, int aux) {
        // Your code here
        long count=0;
        if(N==1) {
            System.out.println("move disk " + N + " from rod " + from + " to rod "+ to);
            return 1;
        }
        
        count+=toh(N-1,from,aux,to);
        
        System.out.println("move disk " + N + " from rod " + from + " to rod "+ to); 
        count+=1;
        
        count+=toh(N-1,aux,to,from);
        
        return count;
    }
}
+3
tikamsingh19019003 weeks ago
C++ , program.
 
 long long toh(int N, int from, int to, int aux) {long long count=0;  if(N==0)  {      return 0;  }  if(N>0)  {         count+=toh(N-1,from,aux,to);      cout<<"move disk "<<N<<" from rod "<<from<<" to rod "<<to<<endl;      count+=toh(N-1,aux,to,from);  }  return count+1;   }
0
h3h33 weeks ago
   if(N==0)       {           return 1;       }        toh(N-1, from, aux, to);                System.out.println("move disk "+ N + " from rod "+ from+ " to rod "+ to);                 toh(N-1, aux,to,from);                  long num=(long)(Math.pow(2,N))-1;                  return num;
0
annanyamathur1 month ago
long long toh(int n, int from, int to, int aux) {       if(n==1)       { cout<<"move disk "<<n<<" from rod "<<from <<" to rod "<<to<<endl;       return 1;   }       long long int a=toh(n-1,from,aux,to)+1;       cout<<"move disk "<<n<<" from rod "<<from <<" to rod "<<to<<endl;       long long int b=a+toh(n-1,aux,to,from);       return b;   }
0
lawbindpandey01w1 month ago
long long toh(int N, int from, int to, int aux) {       // Your code here              if(N == 1){           printf("move disk 1 from rod %d to rod %d\n",from, to);           return 1;       }       long long count = 1;       count += toh(N-1,from, aux, to);       printf("move disk %d from rod %d to rod %d\n",N, from, to);       count += toh(N-1, aux, to, from);              return count;          }
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