convert another one to basic string

Author: lrvideckis

library/data_structures/dsu/range_parallel_equivalence_classes.hpp

@@ -5,13 +5,11 @@
 //! @time O((n + q) * \alpha(n))
 //! @space O(n + q)
 UF get_rp_dsu(const vector<array<int, 3>>& rests, int n) {
-  vector<vector<array<int, 2>>> rests_by_len(n + 1);
-  for (auto [l1, l2, len] : rests)
-    rests_by_len[len].push_back({l1, l2});
+  vector<basic_string<array<int, 2>>> rests_by_len(n + 1);
+  for (auto [l1, l2, len] : rests) rests_by_len[len] += {l1, l2};
   UF uf(n);
   for (int len = n; len > 0; len--)
     for (auto [l1, l2] : rests_by_len[len])
-      if (uf.join(l1, l2))
-        rests_by_len[len - 1].push_back({l1 + 1, l2 + 1});
+      if (uf.join(l1, l2)) rests_by_len[len - 1] += {l1 + 1, l2 + 1};
   return uf;
 }