1 files changed, 27 insertions, 0 deletions
diff --git a/content/geometry/closestPair.cpp b/content/geometry/closestPair.cpp
new file mode 100644
index 0000000..9b115f3
--- /dev/null
+++ b/content/geometry/closestPair.cpp
@@ -0,0 +1,27 @@
+ll rec(vector<pt>::iterator a, int l, int r) {
+	if (r - l < 2) return INF;
+	int m = (l + r) / 2;
+	ll midx = a[m].real();
+	ll ans = min(rec(a, l, m), rec(a, m, r));
+
+	inplace_merge(a+l, a+m, a+r, [](const pt& x, const pt& y) {
+		return x.imag() < y.imag();
+	});
+
+	pt tmp[8];
+	fill(all(tmp), a[l]);
+	for (int i = l + 1, next = 0; i < r; i++) {
+		if (ll x = a[i].real() - midx; x * x < ans) {
+			for (pt& p : tmp) ans = min(ans, norm(p - a[i]));
+			tmp[next++ & 7] = a[i];
+		}
+	}
+	return ans;
+}
+
+ll shortestDist(vector<pt> a) { // sz(pts) > 1
+	sort(all(a), [](const pt& x, const pt& y) {
+		return x.real() < y.real();
+	});
+	return rec(a.begin(), 0, sz(a));
+}