Nits (#199)

* make function

* [auto-verifier] verify commit f0d14b6

* add more comments

---------

Co-authored-by: GitHub <noreply@github.com>

Author: lrvideckis

.verify-helper/timestamps.remote.json

@@ -77,7 +77,7 @@
 "tests/library_checker_aizu_tests/handmade_tests/dsu.test.cpp": "2026-01-22 10:08:22 -0700",
 "tests/library_checker_aizu_tests/handmade_tests/edge_cd_small_trees.test.cpp": "2026-03-16 14:36:46 -0600",
 "tests/library_checker_aizu_tests/handmade_tests/fib_matrix_expo.test.cpp": "2026-01-28 21:48:16 -0700",
-"tests/library_checker_aizu_tests/handmade_tests/functional_graph.test.cpp": "2025-08-06 16:18:37 -0600",
+"tests/library_checker_aizu_tests/handmade_tests/functional_graph.test.cpp": "2026-03-24 10:50:28 -0600",
 "tests/library_checker_aizu_tests/handmade_tests/hilbert_mos.test.cpp": "2026-01-18 02:20:40 +0000",
 "tests/library_checker_aizu_tests/handmade_tests/kd_bit.test.cpp": "2026-02-19 18:06:52 -0700",
 "tests/library_checker_aizu_tests/handmade_tests/manacher.test.cpp": "2026-01-18 11:15:41 +0000",

library/data_structures_[l,r)/seg_tree.hpp

@@ -7,10 +7,12 @@
 //!   });
 //!   tree st(n, LLONG_MAX, ranges::min);
 //!   st.max_right(l, r, [&](int m, ll value) {
+//!     // l < m <= r
 //!     // value = op(a[l], a[l+1], ..., a[m-1])
 //!     return value <= x;
 //!   });
 //!   st.min_left(l, r, [&](int m, ll value) {
+//!     // l <= m < r
 //!     // value = op(a[m], ..., a[r-2], a[r-1])
 //!     return value <= x;
 //!   });

library/data_structures_[l,r]/seg_tree.hpp

@@ -6,10 +6,12 @@
 //!   });
 //!   tree st(n, LLONG_MAX, ranges::min);
 //!   st.max_right(l, r, [&](int m, ll value) {
+//!     // l <= m <= r
 //!     // value = op(a[l], a[l+1], ..., a[m])
 //!     return value <= x;
 //!   });
 //!   st.min_left(l, r, [&](int m, ll value) {
+//!     // l <= m <= r
 //!     // value = op(a[m], ..., a[r-1], a[r])
 //!     return value <= x;
 //!   });

library/graphs/uncommon/functional_graph_processor.hpp

@@ -11,25 +11,25 @@
 //! t[v].childs = forest of reversed edges not in cycles
 //! @time O(n)
 //! @space O(n)
-struct func_graph {
-  vector<pii> root_of;
-  vector<vi> cycle, childs;
-  func_graph(const vi& a): root_of(sz(a)), childs(sz(a)) {
-    vi vis(sz(a));
-    rep(i, 0, sz(a)) if (!vis[i]) {
-      int u = i;
-      for (; !vis[u]; u = a[u]) vis[u] = 1;
-      if (vis[u] == 1)
-        for (cycle.emplace_back(); vis[u] == 1; u = a[u]) {
-          root_of[u] = {sz(cycle) - 1, sz(cycle.back())};
-          cycle.back().push_back(u);
-          vis[u] = 2;
-        }
-      for (int v = i; vis[v] == 1; v = a[v]) {
-        root_of[v] = root_of[u];
-        childs[a[v]].push_back(v);
-        vis[v] = 2;
+auto func_graph(const vi& a) {
+  int n = sz(a);
+  vector<pii> root_of(n);
+  vector<vi> cycle, childs(n);
+  vi vis(n);
+  rep(i, 0, n) if (!vis[i]) {
+    int u = i;
+    for (; !vis[u]; u = a[u]) vis[u] = 1;
+    if (vis[u] == 1)
+      for (cycle.emplace_back(); vis[u] == 1; u = a[u]) {
+        root_of[u] = {sz(cycle) - 1, sz(cycle.back())};
+        cycle.back().push_back(u);
+        vis[u] = 2;
       }
+    for (int v = i; vis[v] == 1; v = a[v]) {
+      root_of[v] = root_of[u];
+      childs[a[v]].push_back(v);
+      vis[v] = 2;
     }
   }
-};
+  return tuple{root_of, cycle, childs};
+}