Hi,

I've been trying to solve a problem in combinations. I have a matrix 6X6 i'm trying to find all combinations of length 8 in the matrix.

I have to move from neighbor to neighbor form each row,column position and i wrote a recursive program which generates the combination but the problem is it generates a lot of duplicates as well and hence is inefficient. I would like to know how could i eliminate calculating duplicates and save time.

int a={{1,2,3,4,5,6},
   {8,9,1,2,3,4},
   {5,6,7,8,9,1},
   {2,3,4,5,6,7},
   {8,9,1,2,3,4},
   {5,6,7,8,9,1},
  }

 void genSeq(int row,int col,int length,int combi)
 {
    if(length==8)
    {
      printf("%d\n",combi);
      return;
    }
    combi = (combi * 10) + a[row][col];
    if((row-1)>=0)

    genSeq(row-1,col,length+1,combi);

if((col-1)>=0)

    genSeq(row,col-1,length+1,combi);

if((row+1)<6)

    genSeq(row+1,col,length+1,combi);

if((col+1)<6)

    genSeq(row,col+1,length+1,combi);

if((row+1)<6&&(col+1)<6)

    genSeq(row+1,col+1,length+1,combi);

if((row-1)>=0&&(col+1)<6)

    genSeq(row-1,col+1,length+1,combi);

if((row+1)<6&&(row-1)>=0)

    genSeq(row+1,col-1,length+1,combi);

if((row-1)>=0&&(col-1)>=0)

    genSeq(row-1,col-1,length+1,combi);
   }

I was also thinking of writing a dynamic program basically recursion with memorization. Is it a better choice?? if yes than I'm not clear how to implement it in recursion. Have i really hit a dead end with approach???

Thankyou

Edit Eg result 12121212,12121218,12121219,12121211,12121213.

the restrictions are that you have to move to your neighbor from any point, you have to start for each position in the matrix i.e each row,col. you can move one step at a time, i.e right, left, up, down and the both diagonal positions. Check the if conditions. i.e if your in (0,0) you can move to either (1,0) or (1,1) or (0,1) i.e three neighbors. if your in (2,2) you can move to eight neighbors.
so on...