From 1385bf25d24df9d8d6618832f549cdeb786e16f5 Mon Sep 17 00:00:00 2001
From: Luke Videckis <lukevideckis@gmail.com>
Date: Wed, 27 Nov 2024 19:29:50 -0600
Subject: [PATCH] fix

---
 library/graphs/functional_graph_processor.hpp   | 12 ++++++------
 .../handmade_tests/functional_graph.test.cpp    | 17 +++++++++++------
 2 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/library/graphs/functional_graph_processor.hpp b/library/graphs/functional_graph_processor.hpp
index 71792d3e..1cf187b9 100644
--- a/library/graphs/functional_graph_processor.hpp
+++ b/library/graphs/functional_graph_processor.hpp
@@ -3,7 +3,8 @@
 //! @code
 //!   // 0 <= a[i] < n
 //!   auto [t2, cycle] = func_graph(a);
-//!   int root = cycle[t2[v].i][t2[v].j];
+//!   auto [cyc_id, cyc_pos] = t2[v].root_of;
+//!   int root = cycle[cyc_id][cyc_pos];
 //!   bool is_on_cycle = (v == root);
 //! @endcode
 //! root = first reachable node on cycle
@@ -12,7 +13,7 @@
 //! @space O(n)
 struct func_graph {
   struct node {
-    int i, j;
+    pii root_of;
     vi childs;
   };
   vector<node> t;
@@ -29,8 +30,8 @@ struct func_graph {
         if (state[u] == 1) {
           cycle.emplace_back();
           while (state[u] == 1) {
-            t[u].i = sz(cycle) - 1;
-            t[u].j = sz(cycle.back());
+            t[u].root_of = {
+              sz(cycle) - 1, sz(cycle.back())};
             cycle.back().push_back(u);
             state[u] = 2;
             u = a[u];
@@ -38,8 +39,7 @@ struct func_graph {
         }
         int v = i;
         while (state[v] == 1) {
-          t[v].i = t[u].i;
-          t[v].j = t[u].j;
+          t[v].root_of = t[u].root_of;
           t[a[v]].childs.push_back(v);
           state[v] = 2;
           v = a[v];
diff --git a/tests/library_checker_aizu_tests/handmade_tests/functional_graph.test.cpp b/tests/library_checker_aizu_tests/handmade_tests/functional_graph.test.cpp
index 99486432..2eb214a2 100644
--- a/tests/library_checker_aizu_tests/handmade_tests/functional_graph.test.cpp
+++ b/tests/library_checker_aizu_tests/handmade_tests/functional_graph.test.cpp
@@ -129,17 +129,22 @@ int main() {
     functional_graph_processor fgp(a);
     assert(cycle == fgp.cycle);
     for (int i = 0; i < n; i++) {
-      int root = cycle[t[i].i][t[i].j];
+      int root =
+        cycle[t[i].root_of.first][t[i].root_of.second];
       assert(t[i].childs == fgp.abr[i]);
       assert((root == i) == (fgp.cycle_id[i] != -1));
       if (root == i) {
-        assert(t[i].i == fgp.cycle_id[i]);
-        assert(t[i].j == fgp.cycle_pos[i]);
-        int cyc_len = ssize(cycle[t[i].i]);
+        assert(t[i].root_of.first == fgp.cycle_id[i]);
+        assert(t[i].root_of.second == fgp.cycle_pos[i]);
+        int cyc_len = ssize(cycle[t[i].root_of.first]);
         assert(
-          cycle[t[i].i][(t[i].j + 1) % cyc_len] == a[i]);
+          cycle[t[i].root_of.first]
+               [(t[i].root_of.second + 1) % cyc_len] ==
+          a[i]);
         assert(fgp.cycle_prev[i] ==
-          cycle[t[i].i][(t[i].j - 1 + cyc_len) % cyc_len]);
+          cycle[t[i].root_of.first]
+               [(t[i].root_of.second - 1 + cyc_len) %
+                 cyc_len]);
       } else {
         assert(fgp.cycle_prev[i] == -1);
       }