Implemtation of 8 queen problem in C.

Here is the code..

# include <stdio.h>

# include <stdlib.h>

# include <time.h>

int N;  //For N * N ChessBoard

int flag;

void printArray(int a[]);        /* Just to Print the Final Solution */

void getPositions(int a[],int n1,int n2);  /* The Recursive Function */

int main()

{int *a;

 int ctr=0;

 printf("\nTHE N QUEENS PROBLEM ");

 printf("\nNumber Of Rows(N) For NxN Chessboard.");

 scanf("%d",&N);

 a=(int *)(malloc(sizeof(int)*N));

 printf("\nAll possible Solutions ..  \n");

 printf("\nIn Each of the solutions the Coordinates of the N-Queens are given (Row,Col) .");

 printf("\nNote that the Rows and Colums are numbered between 1 - N :\n"); 

 for(ctr=0;ctr<N;ctr++)

 getPositions(a,0,ctr);

 getchar();

 getchar();

}

void printArray(int a[])

{

  int i,choice;

  static int counter=0;

  counter++;                        

 printf("\nSOLUTION # %d :",counter);

 for(i=0;i<N;i++)

 printf("(%d,%d) ",i+1,a[i]+1);

 if(counter%10==0) { printf("\nEnter 0 to exit , 1 to continue .");

    scanf("%d",&choice);

    if(choice==0) exit(0);

    };

}

void getPositions(int a1[],int colno,int val)

{ int ctr1,ctr2;

  a1[colno]=val;

  if(colno==N-1)

{ printArray(a1) ; return;

};

  for(ctr1=0;ctr1<N;)

  {      /* This Loop Finds Suitable Column Numbers , in the NEXT ROW */

   for(ctr2=0;ctr2<=colno;ctr2++)

   if(a1[ctr2]==ctr1 || (colno+1-ctr2)*(colno+1-ctr2)==(ctr1-a1[ctr2])*(ctr1-a1[ctr2]))

   goto miss1;

   getPositions(a1,colno+1,ctr1);

   miss1:

   ctr1++;

   }

}