CareerCup

Binomial coefficient C(x2-x1+y2-y1, x2-x1) ?

public int CountNoOfPaths(int x1, int y1, int x2, int y2)
{
if (x1 == x2 && y1 == y2)
return 1;

if ((x1 > x2 && y1 < y2) || (x1 < x2 && y1 > y2))
return 0;

return CountNoOfPaths(x1 + 1, y1, x2, y2) + CountNoOfPaths(x1, y1 + 1, x2, y2);
}

public int CountNoOfPaths(int x1, int y1, int x2, int y2){

int Distance = x2-x1+y2-y1;

if (x1 <= x2 || y1 <= y2)
return 0;
else if ( x2 <= x1 || y2 <= y1 ) { return Distance}
else{
count = CountNoOfPaths( x1+1, x2, y1, y2 ) + CountNoOfPaths( x1, x2, y1+1, y2 );
return count;
}
}