tree dir reorg

Author: lrvideckis

…brary/trees/uncommon/centroid_decomp.hpp library/trees/centroid_decomp.hpplibrary/trees/uncommon/centroid_decomp.hpp renamed to library/trees/centroid_decomp.hpp library/trees/uncommon/centroid_decomp.hpp renamed to library/trees/centroid_decomp.hpp

@@ -2,9 +2,48 @@
   "https://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ITP1_1_A"
 #include "../template.hpp"
 #include "../../../library/contest/random.hpp"
-#include "../../../library/trees/uncommon/count_paths_per_node.hpp"
+//! @param adj unrooted, connected forest
+//! @param k number of edges
+//! @returns array `num_paths` where `num_paths[i]` =
+//! number of paths with k edges where node `i` is on the
+//! path. 0-based nodes.
+//! @time O(n log n)
+//! @space this function allocates/returns various vectors
+//! which are all O(n)
+vector<ll> count_paths_per_node(const vector<vi>& adj,
+  int k) {
+  vector<ll> num_paths(sz(adj));
+  centroid(adj,
+    [&](const vector<vi>& cd_adj, int cent, int) {
+      vector pre_d{1}, cur_d{0};
+      auto dfs = [&](auto&& self, int u, int p,
+                   int d) -> ll {
+        if (d > k) return 0LL;
+        if (sz(cur_d) <= d) cur_d.push_back(0);
+        cur_d[d]++;
+        ll cnt = 0;
+        if (k - d < sz(pre_d)) cnt += pre_d[k - d];
+        for (int c : cd_adj[u])
+          if (c != p) cnt += self(self, c, u, d + 1);
+        num_paths[u] += cnt;
+        return cnt;
+      };
+      auto dfs_child = [&](int child) -> ll {
+        ll cnt = dfs(dfs, child, cent, 1);
+        pre_d.resize(sz(cur_d));
+        for (int i = 1; i < sz(cur_d) && cur_d[i]; i++)
+          pre_d[i] += cur_d[i], cur_d[i] = 0;
+        return cnt;
+      };
+      for (int child : cd_adj[cent])
+        num_paths[cent] += dfs_child(child);
+      pre_d = cur_d = {0};
+      for (int child : cd_adj[cent] | views::reverse)
+        dfs_child(child);
+    });
+  return num_paths;
+}
 #include "../../../library/trees/lca_rmq.hpp"
-#include "../../../library/trees/uncommon/count_paths_per_length.hpp"
 #include "../cd_asserts.hpp"
 vector<vector<ll>> naive(const vector<vi>& adj) {
   LCA lc(adj);

library/trees/uncommon/contour_range_query.hpp

@@ -1,7 +1,34 @@
 #define PROBLEM \
   "https://judge.yosupo.jp/problem/frequency_table_of_tree_distance"
 #include "../template.hpp"
-#include "../../../library/trees/uncommon/count_paths_per_length.hpp"
+#include "../../../kactl/content/numerical/FastFourierTransform.h"
+#include "../../../library/trees/edge_cd.hpp"
+//! @param adj unrooted, connected tree
+//! @returns array `num_paths` where `num_paths[i]` = # of
+//! paths in tree with `i` edges. `num_paths[1]` = # edges
+//! @time O(n * logφ(n) * log2(n))
+//! @space this function allocates/returns various vectors
+//! which are each O(n)
+vector<ll> count_paths_per_length(const vector<vi>& adj) {
+  vector<ll> num_paths(sz(adj));
+  if (sz(adj) >= 2) num_paths[1] = sz(adj) - 1;
+  edge_cd(adj,
+    [&](const vector<vi>& cd_adj, int cent, int split) {
+      vector<vector<double>> cnt(2, vector<double>(1));
+      auto dfs = [&](auto&& self, int u, int p, int d,
+                   int side) -> void {
+        if (sz(cnt[side]) == d) cnt[side].push_back(0.0);
+        cnt[side][d]++;
+        for (int c : cd_adj[u])
+          if (c != p) self(self, c, u, 1 + d, side);
+      };
+      rep(i, 0, sz(cd_adj[cent]))
+        dfs(dfs, cd_adj[cent][i], cent, 1, i < split);
+      vector<double> prod = conv(cnt[0], cnt[1]);
+      rep(i, 0, sz(prod)) num_paths[i] += llround(prod[i]);
+    });
+  return num_paths;
+}
 int main() {
   cin.tie(0)->sync_with_stdio(0);
   int n;