another one

Author: lrvideckis

library/graphs/bridges_cuts/block_vertex_tree.hpp

@@ -9,7 +9,7 @@
 //!   }
 //!   vector<basic_string<array<int, 2>>> adj(n);
 //!   auto [num_bccs, bcc_id, is_cut] = cuts(adj, m);
-//!   vector<vi> bvt = block_vertex_tree(adj,
+//!   auto bvt = block_vertex_tree(adj,
 //!     num_bccs, bcc_id);
 //!
 //!   //to loop over each unique bcc containing a node u:
@@ -23,18 +23,18 @@
 //! [n, n + num_bccs) are BCC nodes
 //! @time O(n + m)
 //! @time O(n)
-vector<vi> block_vertex_tree(const auto& adj, int num_bccs,
+auto block_vertex_tree(const auto& adj, int num_bccs,
   const vi& bcc_id) {
   int n = sz(adj);
-  vector<vi> bvt(n + num_bccs);
+  vector<basic_string<int>> bvt(n + num_bccs);
   vector<bool> vis(num_bccs);
   rep(i, 0, n) {
     for (auto [_, e_id] : adj[i]) {
       int bccid = bcc_id[e_id];
       if (!vis[bccid]) {
         vis[bccid] = 1;
-        bvt[i].push_back(bccid + n);
-        bvt[bccid + n].push_back(i);
+        bvt[i] += bccid + n;
+        bvt[bccid + n] += i;
       }
     }
     for (int bccid : bvt[i]) vis[bccid - n] = 0;

tests/library_checker_aizu_tests/graphs/biconnected_components.test.cpp

@@ -16,8 +16,7 @@ int main() {
     edges[i] = make_pair(u, v);
   }
   auto [num_bccs, bcc_id, is_cut] = cuts(adj, m);
-  vector<vector<int>> bvt =
-    block_vertex_tree(adj, num_bccs, bcc_id);
+  auto bvt = block_vertex_tree(adj, num_bccs, bcc_id);
   assert(
     find(begin(bcc_id), end(bcc_id), -1) == end(bcc_id));
   for (int i = 0; i < n; i++) {