lots of nits

Author: lrvideckis

library/dsu/kruskal_tree.hpp

@@ -7,11 +7,9 @@ struct kr_tree {
   vi p;
   vector<vi> adj;
   kr_tree(int n): id(n), p(2 * n, -1), adj(2 * n) {}
-  int find(int v) {
-    return p[v] < 0 ? v : p[v] = find(p[v]);
-  }
+  int f(int v) { return p[v] < 0 ? v : p[v] = f(p[v]); }
   bool join(int u, int v) {
-    if ((u = find(u)) == (v = find(v))) return 0;
+    if ((u = f(u)) == (v = f(v))) return 0;
     return adj[p[u] = p[v] = id++] = {u, v}, 1;
   }
 };

library/dsu/range_parallel_dsu.hpp

@@ -1,31 +1,28 @@
 #pragma once
 #include "dsu.hpp"
-//! Given l1,l2,len; joins (l1,l2), (l1+1,l2+1),
-//!   ..., (l1+len-1,l2+len-1)
+//! Given u,v,len; joins (u,v), (u+1,v+1),
+//!   ..., (u+len-1,v+len-1)
 //! `f` is called at most n-1 times
 //! @time O(n*log(n)*\alpha(n) + q)
 //! @space O(n log n)
 struct rp_dsu {
   vector<DSU> dsus;
   rp_dsu(int n): dsus(bit_width(unsigned(n)), DSU(n)) {}
-  void join(int l1, int l2, int len, const auto& f) {
-    if (len == 0) return;
-    int lg = __lg(len);
-    join_impl(lg, l1, l2, f);
-    join_impl(lg, l1 + len - (1 << lg),
-      l2 + len - (1 << lg), f);
+  void join(int u, int v, int len, const auto& f) {
+    int i = __lg(len);
+    join(u, v, f, i);
+    join(u + len - (1 << i), v + len - (1 << i), f, i);
   }
-  void join_impl(int lvl, int u, int v, const auto& f) {
-    if (lvl == 0) {
+  void join(int u, int v, const auto& f, int i) {
+    if (i == 0) {
       u = dsus[0].f(u);
       v = dsus[0].f(v);
       if (!dsus[0].join(v, u)) return;
       int w = dsus[0].f(u);
       return f(w, u ^ v ^ w);
     }
-    if (!dsus[lvl].join(u, v)) return;
-    join_impl(lvl - 1, u, v, f);
-    join_impl(lvl - 1, u + (1 << (lvl - 1)),
-      v + (1 << (lvl - 1)), f);
+    if (!dsus[i].join(u, v)) return;
+    join(u, v, f, i - 1);
+    join(u + (1 << (i - 1)), v + (1 << (i - 1)), f, i - 1);
   }
 };

library/dsu/range_parallel_equivalence_classes.hpp

@@ -1,17 +1,23 @@
 #pragma once
 #include "dsu.hpp"
-//! Given triplets (l1,l2,len); joins (l1,l2),
-//!   (l1+1,l2+1), ..., (l1+len-1,l2+len-1)
+//! @code
+//!   vector<vector<pii>> joins(n + 1);
+//!   joins[len].emplace_back(u, v);
+//!   // it does:
+//!   // dsu.join(u + 0, v + 0);
+//!   // dsu.join(u + 1, v + 1);
+//!   // dsu.join(u + 2, v + 2);
+//!   // ...
+//!   // dsu.join(u + len - 1, v + len - 1);
+//!   DSU dsu = get_rp_dsu(joins, n);
+//! @endcode
 //! @time O((n + q) * \alpha(n))
 //! @space O(n + q)
-DSU get_rp_dsu(const vector<array<int, 3>>& rests, int n) {
-  vector<vector<pii>> rests_by_len(n + 1);
-  for (auto [l1, l2, len] : rests)
-    rests_by_len[len].emplace_back(l1, l2);
+DSU get_rp_dsu(vector<vector<pii>>& joins, int n) {
   DSU dsu(n);
-  for (int len = n; len > 0; len--)
-    for (auto [l1, l2] : rests_by_len[len])
-      if (dsu.join(l1, l2))
-        rests_by_len[len - 1].emplace_back(l1 + 1, l2 + 1);
+  for (int i = n; i; i--)
+    for (auto [u, v] : joins[i])
+      if (dsu.join(u, v))
+        joins[i - 1].emplace_back(u + 1, v + 1);
   return dsu;
 }

…_aizu_tests/data_structures/dsu.test.cpp …rary_checker_aizu_tests/dsu/dsu.test.cpptests/library_checker_aizu_tests/data_structures/dsu.test.cpp renamed to tests/library_checker_aizu_tests/dsu/dsu.test.cpp tests/library_checker_aizu_tests/data_structures/dsu.test.cpp renamed to tests/library_checker_aizu_tests/dsu/dsu.test.cpp

@@ -18,17 +18,16 @@ int main() {
     ans = (ans + 1LL * x[u] * x[v]) % mod;
     x[u] = (x[u] + x[v]) % mod;
   };
-  vector<array<int, 3>> queries;
-  queries.reserve(q);
+  vector<vector<pii>> joins(n + 1);
   for (int qq = 0; qq < q; qq++) {
     int k, a, b;
     cin >> k >> a >> b;
-    dsu.join(a, b, k, f);
-    queries.push_back({a, b, k});
+    if (k) dsu.join(a, b, k, f);
+    joins[k].emplace_back(a, b);
     cout << ans << '\n';
     if (qq == 0 || qq == 1 || qq == 10 || qq == 1000 ||
       qq == 100'000 || qq == q - 1) {
-      auto uf = get_rp_dsu(queries, n);
+      auto uf = get_rp_dsu(joins, n);
       vi sums(n);
       int offline_ans = 0;
       for (int i = 0; i < n; i++) {