modernc.org/ccgo/v3@v3.16.14/lib/testdata/tcc-0.9.27/tests/tests2/30_hanoi.c (about)

     1  /* example from http://barnyard.syr.edu/quickies/hanoi.c */
     2  
     3  /* hanoi.c: solves the tower of hanoi problem. (Programming exercise.) */
     4  /* By Terry R. McConnell (12/2/97) */
     5  /* Compile: cc -o hanoi hanoi.c */
     6  
     7  /* This program does no error checking. But then, if it's right, 
     8     it's right ... right ? */
     9  
    10  
    11  /* The original towers of hanoi problem seems to have been originally posed
    12     by one M. Claus in 1883. There is a popular legend that goes along with
    13     it that has been often repeated and paraphrased. It goes something like this:
    14     In the great temple at Benares there are 3 golden spikes. On one of them,
    15     God placed 64 disks increasing in size from bottom to top, at the beginning
    16     of time. Since then, and to this day, the priest on duty constantly transfers
    17     disks, one at a time, in such a way that no larger disk is ever put on top
    18     of a smaller one. When the disks have been transferred entirely to another
    19     spike the Universe will come to an end in a large thunderclap.
    20  
    21     This paraphrases the original legend due to DeParville, La Nature, Paris 1884,
    22     Part I, 285-286. For this and further information see: Mathematical 
    23     Recreations & Essays, W.W. Rouse Ball, MacMillan, NewYork, 11th Ed. 1967,
    24     303-305.
    25   *
    26   *
    27   */
    28  
    29  #include <stdio.h>
    30  #include <stdlib.h>
    31  
    32  #define TRUE 1
    33  #define FALSE 0
    34  
    35  /* This is the number of "disks" on tower A initially. Taken to be 64 in the
    36   * legend. The number of moves required, in general, is 2^N - 1. For N = 64,
    37   * this is 18,446,744,073,709,551,615 */
    38  #define N 4
    39  
    40  /* These are the three towers. For example if the state of A is 0,1,3,4, that
    41   * means that there are three discs on A of sizes 1, 3, and 4. (Think of right
    42   * as being the "down" direction.) */
    43  int A[N], B[N], C[N]; 
    44  
    45  void Hanoi(int,int*,int*,int*);
    46  
    47  /* Print the current configuration of A, B, and C to the screen */
    48  void PrintAll()
    49  {
    50     int i;
    51  
    52     printf("A: ");
    53     for(i=0;i<N;i++)printf(" %d ",A[i]);
    54     printf("\n");
    55  
    56     printf("B: ");
    57     for(i=0;i<N;i++)printf(" %d ",B[i]);
    58     printf("\n");
    59  
    60     printf("C: ");
    61     for(i=0;i<N;i++)printf(" %d ",C[i]);
    62     printf("\n");
    63     printf("------------------------------------------\n");
    64     return;
    65  }
    66  
    67  /* Move the leftmost nonzero element of source to dest, leave behind 0. */
    68  /* Returns the value moved (not used.) */
    69  int Move(int *source, int *dest)
    70  {
    71     int i = 0, j = 0;
    72  
    73     while (i<N && (source[i])==0) i++;
    74     while (j<N && (dest[j])==0) j++;
    75  
    76     dest[j-1] = source[i];
    77     source[i] = 0;
    78     PrintAll();       /* Print configuration after each move. */
    79     return dest[j-1];
    80  }
    81  
    82  
    83  /* Moves first n nonzero numbers from source to dest using the rules of Hanoi.
    84     Calls itself recursively.
    85     */
    86  void Hanoi(int n,int *source, int *dest, int *spare)
    87  {
    88     int i;
    89     if(n==1){
    90        Move(source,dest);
    91        return;
    92     }
    93  
    94     Hanoi(n-1,source,spare,dest);
    95     Move(source,dest);
    96     Hanoi(n-1,spare,dest,source);	
    97     return;
    98  }
    99  
   100  int main()
   101  {
   102     int i;
   103  
   104     /* initialize the towers */
   105     for(i=0;i<N;i++)A[i]=i+1;
   106     for(i=0;i<N;i++)B[i]=0;
   107     for(i=0;i<N;i++)C[i]=0;
   108  
   109     printf("Solution of Tower of Hanoi Problem with %d Disks\n\n",N);
   110  
   111     /* Print the starting state */
   112     printf("Starting state:\n");
   113     PrintAll();
   114     printf("\n\nSubsequent states:\n\n");
   115  
   116     /* Do it! Use A = Source, B = Destination, C = Spare */
   117     Hanoi(N,A,B,C);
   118  
   119     return 0;
   120  }
   121  
   122  /* vim: set expandtab ts=4 sw=3 sts=3 tw=80 :*/