2019.10.26

fck codeforces

Author: EntropyIncreaser

part2/arc101_e.cpp

@@ -0,0 +1,68 @@
+#include <cstdio>
+#include <cstring>
+#include <cstdlib>
+#include <cstring>
+
+#include <algorithm>
+#include <numeric>
+#include <functional>
+#include <vector>
+
+#define LOG(FMT...) fprintf(stderr, FMT)
+
+using namespace std;
+
+typedef long long ll;
+
+const int N = 5010, P = 1000000007;
+
+int n;
+int fac[N];
+int f[N][N];
+int sub[N];
+vector<int> g[N];
+
+void dfs(int u) {
+  sub[u] = 1;
+  f[u][1] = 1;
+  for (int v : g[u])
+    if (!sub[v]) {
+      dfs(v);
+      if (!(sub[v] & 1)) {
+        for (int i = 1; i <= sub[v] / 2; ++i)
+          f[v][0] = (f[v][0] + f[v][i * 2] * (ll)fac[i]) % P;
+        f[v][0] = (P - f[v][0]) % P;
+      }
+      static int tmp[N];
+      memset(tmp, 0, sizeof(tmp));
+      for (int i = 0; i <= sub[u]; ++i)
+        for (int j = 0; j <= sub[v]; ++j)
+          tmp[i + j] = (tmp[i + j] + f[u][i] * (ll)f[v][j]) % P;
+      memcpy(f[u], tmp, sizeof(tmp));
+      sub[u] += sub[v];
+    }
+}
+
+int main() {
+#ifdef LBT
+  freopen("test.in", "r", stdin);
+#endif
+
+  scanf("%d", &n);
+  for (int rep = 1; rep < n; ++rep) {
+    int u, v;
+    scanf("%d%d", &u, &v);
+    g[u].push_back(v);
+    g[v].push_back(u);
+  }
+  fac[0] = 1;
+  for (int i = 1; i <= n; ++i)
+    fac[i] = fac[i - 1] * (2 * i - 1LL) % P;
+  dfs(1);
+  int ans = 0;
+  for (int i = 0; i <= n / 2; ++i)
+    ans = (ans + fac[i] * (ll)f[1][i * 2]) % P;
+  printf("%d\n", ans);
+
+  return 0;
+}

part2/arc101_f.cpp

@@ -0,0 +1,114 @@
+#include <cstdio>
+#include <cstring>
+#include <cstdlib>
+#include <cmath>
+#include <ctime>
+#include <cctype>
+
+#include <algorithm>
+#include <random>
+#include <bitset>
+#include <queue>
+#include <functional>
+#include <set>
+#include <map>
+#include <vector>
+#include <chrono>
+#include <iostream>
+#include <limits>
+#include <numeric>
+
+#define LOG(FMT...) fprintf(stderr, FMT)
+
+using namespace std;
+
+typedef long long ll;
+typedef unsigned long long ull;
+
+// mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
+
+template <class T>
+istream& operator>>(istream& is, vector<T>& v) {
+  for (T& x : v)
+    is >> x;
+  return is;
+}
+
+template <class T>
+ostream& operator<<(ostream& os, const vector<T>& v) {
+  if (!v.empty()) {
+    os << v.front();
+    for (int i = 1; i < v.size(); ++i)
+      os << ' ' << v[i];
+  }
+  return os;
+}
+
+const int N = 100010, P = 1000000007;
+
+int n, m, cnt;
+int x[N], y[N], dx[N];
+pair<int, int> a[N];
+int fw[N];
+
+void add(int& x, int y) {
+  if ((x += y) >= P)
+    x -= P;
+}
+
+int norm(int x) { return x >= P ? (x - P) : x; }
+
+int lowBit(int k) { return k & -k; }
+
+void ch(int k, int x) {
+  for (; k <= cnt; k += lowBit(k))
+    add(fw[k], x);
+}
+
+int qry(int k) {
+  int ret = 0;
+  while (k) {
+    add(ret, fw[k]);
+    k &= k - 1;
+  }
+  return ret;
+}
+
+int main() {
+#ifdef LBT
+  freopen("test.in", "r", stdin);
+  int nol_cl = clock();
+#endif
+  ios::sync_with_stdio(false);
+  cin.tie(nullptr);
+
+  cin >> n >> m;
+  for (int i = 1; i <= n; ++i)
+    cin >> x[i];
+  for (int i = 1; i <= m; ++i)
+    cin >> y[i];
+  for (int i = 1; i <= n; ++i) {
+    if (x[i] < y[1] || x[i] > y[m])
+      continue;
+    int id = lower_bound(y + 1, y + m + 1, x[i]) - y;
+    a[++cnt] = make_pair(x[i] - y[id - 1], y[id] - x[i]);
+    dx[cnt] = a[cnt].second;
+  }
+  int ans = 1;
+  sort(dx + 1, dx + cnt + 1);
+  sort(a + 1, a + cnt + 1, [](const auto& lhs, const auto& rhs) { return lhs.first == rhs.first ? (lhs.second > rhs.second) : (lhs.first < rhs.first); });
+  for (int i = 1; i <= cnt; ++i) {
+    if (a[i] == a[i - 1]) continue;
+    int pos = lower_bound(dx + 1, dx + cnt + 1, a[i].second) - dx;
+    int cur = norm(qry(pos - 1) + 1);
+    add(ans, cur);
+    ch(pos, cur);
+  }
+  cout << ans << '\n';
+
+#ifdef LBT
+  LOG("Time: %dms\n", int ((clock()
+          -nol_cl) / (double)CLOCKS_PER_SEC * 1000));
+#endif
+  return 0;
+}