float ClosestPair(Point* pX, int n){
if(n <= 3) return bruteForce(pX, n);
//Chia mang thanh hai phan bang nhau
int mid = n/2;
Point midPoint = pX[mid];
float dL = ClosestPair(pX, mid);
printf("ClosestPairL %f\n", dL);
float dR = ClosestPair(pX + mid,n-mid);
printf("ClosestPairR %f\n", dR);
float d = min(dL, dR);
printf("ClosestPair %f\n", d);
Point* pLR = (Point*) malloc (n * sizeof(Point));
int k = 0;
for (int i = 0; i < n; ++i){
if (abs(pX[i].x - midPoint.x) <= d){
pLR[k] = pX[i];
k++;
}
}
if (dmin > min(stripClosest(pLR, k, d), d)){
dmin = min(stripClosest(pLR, k, d), d);
}
return min(stripClosest(pLR, k, d), d);;
}
// A recursive function to find the smallest distance. The array P contains
// all points sorted according to x coordinate
float closestUtil(Point P[], int n)
{
// If there are 2 or 3 points, then use brute force
if (n <= 3)
return bruteForce(P, n);
// Find the middle point
int mid = n/2;
Point midPoint = P[mid];
// Consider the vertical line passing through the middle point
// calculate the smallest distance dl on left of middle point and
// dr on right side
float dl = closestUtil(P, mid);
float dr = closestUtil(P + mid, n-mid);
// Find the smaller of two distances
float d = min(dl, dr);
// Build an array strip[] that contains points close (closer than d)
// to the line passing through the middle point
Point strip[n];
int j = 0;
for (int i = 0; i < n; i++)
if (abs(P[i].x - midPoint.x) < d)
strip[j] = P[i], j++;
// Find the closest points in strip. Return the minimum of d and closest
// distance is strip[]
return min(d, stripClosest(strip, j, d) );
}
float closest(point *A,long long N,point *u,point *v)
{
if(N<3)
{
return bruteForce(A,N,u,v);
}
long long mid=N/2;
point midPoint = A[mid];
point a,b,r,s;
long long i,j;
double dl = closest(A, mid,&a,&b);
double dr = closest(A + mid, N-mid,&r,&s);
double d = min(dl, dr);
if(dl<dr)
{
u[0].x=a.x;u[0].y=a.y;
v[0].x=b.x;v[0].y=b.y;
}
else
{
u[0].x=r.x;u[0].y=r.y;
v[0].x=s.x;v[0].y=s.y;
}
point strip[N];
j=0;
for (i = 0; i < N; i++)
if (abs(A[i].x - midPoint.x) < d)
{
strip[j] = A[i];
j++;
}
// return min(d, stripClosest(strip, j, d) );
double minStrip = stripClosest(strip,j,d,&a,&b);
if(d<minStrip)
{
return d;
}
else
{
u[0].x=a.x;u[0].y=a.y;
v[0].x=b.x;v[0].y=b.y;
return minStrip;
}
}
struct PointPair closestpair(struct Point p[],int n)
{
if(n<=3)
return brute(p,n);
int mid=n/2;
struct Point midp=p[mid];
struct PointPair dl = closestpair(p,mid);
struct PointPair dr = closestpair(p+mid,n-mid);
struct PointPair d = minpp(dl,dr);
struct Point strip[n];
int i=0,j = 0;
for (i = 0; i < n; i++)
if (abs(p[i].x - midp.x) < d.dist)
strip[j] = p[i], j++;
return minpp(d,stripClosest(strip,j,d));
}
float closestUtil(Point P[], int n)
{
if (n <= 3)
return bruteForce(P, n);
int mid = n/2;
Point midPoint = P[mid];
float dl = closestUtil(P, mid);
float dr = closestUtil(P + mid, n-mid);
float d = min(dl, dr);
Point strip[n];
int j = 0;
for (int i = 0; i < n; i++)
if (abs(P[i].x - midPoint.x) < d)
strip[j] = P[i], j++;
return min(d, stripClosest(strip, j, d) );
}
