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Traverse Knight in ChessBoard problem

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1. 

   vpshastry
   guest
   Posted 3 months ago #
   
   

   I've written a code to traverse a knight to all the squares on a chess board only once. The problem with this(below) code is, its working till 7x7 and doing nothing after 8x8. The code is
   Here chessBoardSize defines the size(8=> 8x8)

   #include<stdio.h>
   #include<stdlib.h>
   #define chessBoardSize 8
   
   int chessBoard[chessBoardSize][chessBoardSize] = {0};
   typedef struct point{
   	int x, y;
   }POINT;
   int count=0;
   
   int nextPosition(int x, int y, POINT* array){
   	int m=0;
   /* finds the next possible points for the current
      position in the chess board:
      like
      _	_	_	_	_ 	_
      _	*	_	*	_ 	_
      *	_	_	_	* 	_
      _	_	P	_	_ 	_
      *	_	_	_	* 	_
      _	*	_	*	_ 	_  
   
    	as above if 'P' is the current (x,y)
    	* represents the next possible points and
    	also checks it exists within the chess board
   */
   
   	if( (x+2) < chessBoardSize ){
   		if( (y+1) < chessBoardSize ){
   			array[m].x = x+2;
   			array[m++].y = y+1;
   		}
   		if( (y-1) >-1 ){
   			array[m].x = x+2;
   			array[m++].y = y-1;
   		}
   	}
   
   	if( (x-2) > -1){
   		if( (y+1) < chessBoardSize ){
   			array[m].x = x-2;
   			array[m++].y = y+1;
   		}
   		if( (y-1) >-1 ){
   			array[m].x = x-2;
   			array[m++].y = y-1;
   		}
   	}
   
   	if( (y+2) < chessBoardSize){
   		if( (x+1) < chessBoardSize ){
   			array[m].x = x+1;
   			array[m++].y = y+2;
   		}
   		if( (x-1) >-1 ){
   			array[m].x = x-1;
   			array[m++].y = y+2;
   		}
   	}	
   
   	if( (y-2) > -1){
   		if( (x+1) < chessBoardSize ){
   			array[m].x = x+1;
   			array[m++].y = y-2;
   		}
   		if( (x-1) >-1 ){
   			array[m].x = x-1;
   			array[m++].y = y-2;
   		}
   	}
   	return m;
   }
   
   void displayAnswer(){
   	int i, j, k;
   	printf("\n");
   	for(i=0; i<chessBoardSize; i++){
   		for(j=0; j<chessBoardSize; j++)
   			printf("%d\t",chessBoard[i][j]);
   		printf("\n\n");
   	}
   }
   
   //	recursive function using backtrack method
   void knightTravel(int x, int y){
   	POINT array[8] = {{0, 0}, {0, 0}};
   	// remainin initialized to zero automatically
   	volatile int noOfPossiblePoints = nextPosition(x, y, array);
   	volatile int i;
   
   	chessBoard[x][y] = ++count;
   
   	//	base condition uses count
   	if( count == chessBoardSize * chessBoardSize ){
   		displayAnswer();
   		exit(0);
   	}
   
   	for(i=0; i< noOfPossiblePoints; i++)
   		if( chessBoard[array[i].x][array[i].y] == 0 )
   			knightTravel(array[i].x, array[i].y); 
   
   	chessBoard[x][y] = 0;
   	count--;
   }
   
   int main()
   {
   	knightTravel(0, 0);
   	printf("No solution exists\n");
   	return 0;
   }

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