more nits

Author: lrvideckis

library/dsu/line_tree.hpp

@@ -4,14 +4,14 @@
 //!   ranges::sort(w_eds);
 //!   line_tree lt(n);
 //!   for (auto [w, u, v] : w_eds) lt.join(u, v);
-//!   for (int v = lt.find(0); v != -1;) {
+//!   for (int v = lt.f(0); v != -1;) {
 //!     auto [next, e_id] = lt.edge[v];
 //!     int w = w_eds[e_id][0];
 //!     //
 //!     v = next;
 //!   }
 //! @endcode
-//! lt.find(v) = head of linked list
+//! lt.f(v) = head of linked list
 //!   of component containing v
 //! @time O(n + m * \alpha(n))
 //! @space O(n + m)
@@ -22,16 +22,14 @@ struct line_tree {
   line_tree(int n): p(n, -1), last(n), edge(n, {-1, -1}) {
     iota(all(last), 0);
   }
-  int size(int v) { return -p[find(v)]; }
-  int find(int v) {
-    return p[v] < 0 ? v : p[v] = find(p[v]);
-  }
+  int size(int v) { return -p[f(v)]; }
+  int f(int v) { return p[v] < 0 ? v : p[v] = f(p[v]); }
   bool join(int u, int v) {
-    u = find(u), v = find(v), id++;
+    u = f(u), v = f(v), id++;
     if (u == v) return 0;
     if (p[u] < p[v]) swap(u, v);
     p[v] += p[u], p[u] = v;
-    edge[exchange(last[v], last[u])] = {u, id - 1};
+    edge[last[v]] = {u, id - 1}, last[v] = last[u];
     return 1;
   }
 };

tests/library_checker_aizu_tests/dsu/line_tree_aizu.test.cpp

@@ -28,7 +28,7 @@ int main() {
   int mst_sum = 0;
   vector<int> edge_weights;
   vector<int> to_time(n);
-  for (int v = lt.find(0), timer = 1;
+  for (int v = lt.f(0), timer = 1;
     lt.edge[v] != pii{-1, -1};
     v = lt.edge[v].first, timer++) {
     edge_weights.push_back(w_eds[lt.edge[v].second][0]);

tests/library_checker_aizu_tests/dsu/line_tree_lib_checker.test.cpp

@@ -22,7 +22,7 @@ int main() {
   assert(lt.size(0) == n);
   int64_t cost = 0;
   vector<int> ids;
-  for (int v = lt.find(0); lt.edge[v].first != -1;
+  for (int v = lt.f(0); lt.edge[v].first != -1;
     v = lt.edge[v].first) {
     ids.push_back(w_eds[lt.edge[v].second][0]);
     cost += weights[w_eds[lt.edge[v].second][0]];