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);;
}
double ClosestPair(int l, int r, double *dis) {
if(l < r) {
if(l == r-1) {
return (D[l].x-D[r].x)*(D[l].x-D[r].x) + (D[l].y-D[r].y)*(D[l].y-D[r].y);
}
int m = (l+r)>>1;
*dis = Min(*dis, ClosestPair(l, m, dis));
*dis = Min(*dis, ClosestPair(m+1, r, dis));
*dis = Min(*dis, Merge(l, m, r, *dis));
return *dis;
}
return oo;
}
double ClosestPair(std::vector<Point>::const_iterator start,
std::vector<Point>::const_iterator end,
size_t& count,
Point& p1, Point& p2)
{
auto len = std::distance(start, end);
if (len <= 3)
{
return ClosestPairB(start, end, count, p1, p2);
}
else
{
auto splitPos = len / 2;
auto l = start;
auto r = start;
std::advance(r, splitPos);
Point l1, l2, r1, r2;
double dl = ClosestPair(l, r, count, l1, l2);
double dr = ClosestPair(r, end, count, r1, r2);
double minD = std::min(dl, dr);
if (minD == dl)
{
p1 = l1;
p2 = l2;
}
else
{
p1 = r1;
p2 = r2;
}
auto middleX = (std::prev(r)->x + r->x) / 2;
l = std::lower_bound(start, end, Point{ middleX - minD, 0 });
r = std::upper_bound(start, end, Point{ middleX + minD, 0 });
auto d = ClosestPairB(l, r, count, l1, l2);
if (d < minD)
{
minD = d;
p1 = l1;
p2 = l2;
}
return minD;
}
}
void closestpair_test()
{
std::vector<Point> m = { { 2, 7 },
{ 4, 13 },
{ 5, 7 },
{ 10, 5 },
{ 13, 9 },
{ 15, 5 },
{ 17, 7 },
{ 19, 10 },
{ 22, 7 },
{ 25, 10 },
{ 29, 14 },
{ 30, 2 } };
size_t count = 0;
Point p1, p2;
double minD = ClosestPairB(m.begin(), m.end(), count, p1, p2);
std::cout << "Bruteforce: " << count << std::endl;
std::cout << "Min = " << minD << std::endl;
std::sort(m.begin(), m.end());
Point p3, p4;
count = 0;
minD = 0;
minD = ClosestPair(m.begin(), m.end(), count, p3, p4);
std::cout << "Divide: " << count << std::endl;
std::cout << "Min = " << minD << std::endl;
}
int main() {
int N, i, x, y;
ReadInt(&N);
for(i = 0; i < N; i++) {
ReadInt(&x), ReadInt(&y);
D[i].x = x, D[i].y = y;
}
double distance = oo;
distance = ClosestPair(0, N-1, &distance);
distance = sqrt(distance);
printf("%.4lf\n", distance);
return 0;
}
int main(int argc, char const *argv[]){
readFile();
Point* pX = (Point*) malloc(count * sizeof(Point));
mergeSort(p,0,count-1, 1);
printPoint(p);
mergeSort(p,0,count-1, 0);
setPoint(p, pX);
printf("Co %d diem tren mat phang.\n", count);
printPoint(p);
// Timer ti;
// bruteForce(p, count);
// double y = ti.getElapsedTime();
// printf("Thoi gian chay: %f\n",y);
// printf("Hai diem gan nhau nhat la:\nA(%d, %d), B(%d, %d)\n",a.x,a.y,b.x,b.y);
float min = ClosestPair(pX, count);
printf("Khoang cach gan nhat la: %f\n", min);
printf("Hai diem gan nhau nhat la:\nA(%d, %d), B(%d, %d)\n",a.x,a.y,b.x,b.y);
return 0;
}