Compiler/queens.sjava at master · elorense/Compiler · GitHub

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void PrintBoard(int board[], int size);
int Abs(int x);
boolean Legal(int numcols, int board[]);
void Solve(int numcols, int board[], int size);

void main() {
   int size;
   int board[];

   size = Read();
   board = new int[size];

   Solve(1, board,size);
}

void PrintBoard(int board[], int size) {

   int i;
   int j;

   for (i=0; i<size; i++) {
      for (j=0; j<board[i]; j++)
         Print(0);
      Print(1);
      for(j=board[i]+1; j<size; j++)
         Print(0);
      Println();
   }
   Println();
}


int Abs(int x) {
   if (x >= 0)
      return x;
   else
      return  0-x;
}

boolean Legal(int numcols, int board[]) {
   int i;
   int j;
   boolean legal;

   legal = true;

   for (i=0; i < numcols; i++) {
      for (j=i+1; j<numcols; j++) {
 	 if ((board[i] == board[j]) ||
	     (Abs(i-j) == Abs(board[i]-board[j])))
	    legal = false;
      }
   }
   return legal;
}

void Solve(int numcols, int board[], int size) {
   int i;


   if (numcols > size)  {
      PrintBoard(board,size);
      Println();
   }
   else
      for (i=0; i < size; i++) {
         board[numcols-1] = i;
	 if (Legal(numcols, board)) {
	    Solve(numcols+1, board, size);
         }
      }
}