update

poj/2349.arctic-network/main.cc

@@ -0,0 +1,84 @@
+#include <cmath>
+#include <cstdio>
+#include <cstring>
+#include <queue>
+
+using namespace std;
+
+const int S = 100;
+const int P = 500;
+
+struct V {
+  int x;
+  int y;
+  V(int x = 0, int y = 0) : x(x), y(y) {}
+  double operator-(const V &that) const {
+    double dx = this->x - that.x;
+    double dy = this->y - that.y;
+    return sqrt(dx * dx + dy * dy);
+  }
+} outpost[P];
+
+struct E {
+  int u;
+  int v;
+  double len;
+  E(int u, int v, double len) : u(u), v(v), len(len) {}
+  bool operator<(const E &that) const { return this->len > that.len; }
+};
+
+struct UF {
+  int id[P];
+  int sz[P];
+  int cnt;
+} uf;
+
+int find(int i) {
+  if (i == uf.id[i]) return i;
+  int j = find(uf.id[i]);
+  uf.id[i] = j;
+  return j;
+}
+
+void unite(int i, int j) {
+  i = find(i);
+  j = find(j);
+  if (i == j) return;
+  if (uf.sz[i] < uf.sz[j]) {
+    uf.id[i] = j;
+  } else {
+    if (uf.sz[i] == uf.sz[j]) uf.sz[i]++;
+    uf.id[j] = i;
+  }
+  uf.cnt--;
+}
+
+int main() {
+  int n, s, p, k;
+  scanf("%d", &n);
+  while (n--) {
+    scanf("%d %d", &s, &p);
+    for (int i = 0; i < p; i++) {
+      scanf("%d %d", &outpost[i].x, &outpost[i].y);
+      uf.id[i] = i;
+    }
+    memset(uf.sz, 0, sizeof(uf.sz));
+    uf.cnt = p, k = 0;
+    priority_queue<E> pq;
+    for (int i = 0; i < p - 1; i++)
+      for (int j = i + 1; j < p; j++) pq.push(E(i, j, outpost[i] - outpost[j]));
+    double d = 0.;
+    while (1 < uf.cnt) {
+      E e = pq.top(); // No const E & !!! WA * 4
+      pq.pop();
+      if (find(e.u) == find(e.v)) continue;
+      unite(e.u, e.v);
+      if (++k == p - s) {
+        d = e.len;
+        break;
+      }
+    }
+    printf("%.2f\n", d);
+  }
+  return 0;
+}