Just comment on what line is doing what in this code. (This Closest Pair of Points divide and conquer problem)

double closestPair(int l, int r) { if (l >= r) return 1e9; if (l + 1 == r) return dist(points[l], points[r]);

int mid = l + r >> 1; double d = min(closestPair(l, mid), closestPair(mid + 1, r));

int i = l, j = mid + 1, k = 0; //? Point strip[r - l + 1]; //? while (i <= mid && j <= r) { if (points[i] < points[j]) strip[k++] = points[i++]; //? else strip[k++] = points[j++]; } while (i <= mid) strip[k++] = points[i++]; //? while (j <= r) strip[k++] = points[j++]; //? for (int i = 0; i < k; i++) points[l + i] = strip[I]; //?

i = 0; for (int j = l; j <= r; j++) { //? if (abs(points[j].x - points[mid].x) >= d) continue; //? while (i < k - 1 && points[l + i + 1].y < points[j].y) i++; //? for (int t = i; t < k && points[l + t].y - points[j].y < d; t++) { //? if (mid - l >= 1 && r - mid >= 1) { d = min(d, dist(points[mid - 1], points[mid])); d = min(d, dist(points[mid], points[mid + 1])); } } }

return d; } input:

5

0 0

1 1

2 2

3 3

4 4

Output:

1.4.....