no basic_string in library anymore after learning s[s.size()] isn't RTE

library/data_structures/dsu/kruskal_tree.hpp

@@ -5,7 +5,7 @@
 struct kr_tree {
   int id;
   vi p;
-  vector<basic_string<int>> adj;
+  vector<array<int, 2>> adj;
   kr_tree(int n): id(n), p(2 * n, -1), adj(2 * n) {}
   int find(int v) {
     return p[v] < 0 ? v : p[v] = find(p[v]);

library/data_structures/dsu/range_parallel_equivalence_classes.hpp

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

library/data_structures/seg_tree_uncommon/merge_sort_tree.hpp

@@ -2,7 +2,7 @@
 #include "../lazy_seg_tree_midpoint.hpp"
 struct merge_sort_tree {
   int n;
-  vector<basic_string<int>> tree;
+  vector<vi> tree;
   merge_sort_tree(const vi& a): n(sz(a)), tree(2 * n) {
     int pw2 = bit_ceil(size(a));
     rep(i, 0, n) tree[(i + pw2) % n + n] = {a[i]};

library/data_structures/uncommon/mode_query.hpp

@@ -4,7 +4,7 @@ const int b = 318; //!< sqrt(1e5)
 struct mode_query {
   int n;
   vi a, cnt, index_into_index;
-  vector<basic_string<int>> index;
+  vector<vi> index;
   vector<vector<pii>>
     mode_blocks; //!< {mode, cnt} of range of blocks
   //! @param a compressed array: 0 <= a[i] < n
@@ -16,7 +16,7 @@ struct mode_query {
       vector<pii>((n + b - 1) / b)) {
     rep(i, 0, n) {
       index_into_index[i] = sz(index[a[i]]);
-      index[a[i]] += i;
+      index[a[i]].push_back(i);
     }
     for (int start = 0; start < n; start += b) {
       int mode = a[start];

library/data_structures/uncommon/permutation_tree.hpp

@@ -17,13 +17,13 @@ struct perm_tree {
   };
   vector<node> p;
   int root;
-  vector<basic_string<int>> ch;
+  vector<vi> ch;
   bool touches(int u, int v) {
     return p[u].mn_num == p[v].mn_num + p[v].len ||
       p[v].mn_num == p[u].mn_num + p[u].len;
   }
   int allocate(int mn_i, int mn_v, int ln, bool join,
-    const basic_string<int>& chs) {
+    const vi& chs) {
     p.push_back({mn_i, mn_v, ln, join});
     ch.push_back(chs);
     return sz(ch) - 1;
@@ -50,7 +50,7 @@ struct perm_tree {
         if (!empty(ch[u]) && touches(ch[u].back(), v)) {
           p[u].mn_num = min(p[u].mn_num, p[v].mn_num);
           p[u].len += p[v].len;
-          ch[u] += v;
+          ch[u].push_back(v);
           v = u;
           st.pop_back();
           continue;
@@ -73,7 +73,7 @@ struct perm_tree {
           break;
         }
         int min_num = p[v].mn_num;
-        basic_string<int> chs(1 + sz(st) - idx, v);
+        vi chs(1 + sz(st) - idx, v);
         rep(j, idx, sz(st)) min_num =
           min(min_num, p[chs[j - idx] = st[j][0]].mn_num);
         v = allocate(l, min_num, i - l + 1, 0, chs);

library/graphs/bridges_cuts/block_vertex_tree.hpp

@@ -25,15 +25,15 @@
 auto block_vertex_tree(const auto& adj, int num_bccs,
   const vi& bcc_id) {
   int n = sz(adj);
-  vector<basic_string<int>> bvt(n + num_bccs);
+  vector<vi> 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] += bccid + n;
-        bvt[bccid + n] += i;
+        bvt[i].push_back(bccid + n);
+        bvt[bccid + n].push_back(i);
       }
     }
     for (int bccid : bvt[i]) vis[bccid - n] = 0;

library/graphs/bridges_cuts/bridge_tree.hpp

@@ -14,8 +14,9 @@
 //! @space O(n)
 auto bridge_tree(const auto& adj, int num_ccs,
   const vi& br_id, const vi& is_br) {
-  vector<basic_string<int>> tree(num_ccs);
+  vector<vi> tree(num_ccs);
   rep(i, 0, sz(adj)) for (auto [u, e_id] : adj[i]) if (
-    is_br[e_id]) tree[br_id[i]] += br_id[u];
+    is_br[e_id]) tree[br_id[i]]
+    .push_back(br_id[u]);
   return tree;
 }

library/graphs/enumerate_triangles.hpp

@@ -11,10 +11,10 @@ void enumerate_triangles(const vector<pii>& edges, int n,
   auto f) {
   vi deg(n);
   for (auto [u, v] : edges) deg[u]++, deg[v]++;
-  vector<basic_string<int>> adj(n);
+  vector<vi> adj(n);
   for (auto [u, v] : edges) {
     if (tie(deg[u], u) > tie(deg[v], v)) swap(u, v);
-    adj[u] += v;
+    adj[u].push_back(v);
   }
   vector<bool> seen(n);
   for (auto [u, v] : edges) {

library/graphs/functional_graph_processor.hpp

@@ -13,7 +13,7 @@
 //! @space O(n)
 struct func_graph {
   vector<pii> root_of;
-  vector<basic_string<int>> cycle, childs;
+  vector<vi> cycle, childs;
   func_graph(const vi& a): root_of(sz(a)), childs(sz(a)) {
     vi state(sz(a));
     rep(i, 0, sz(a)) if (!state[i]) {
@@ -26,15 +26,15 @@ struct func_graph {
         cycle.emplace_back();
         while (state[u] == 1) {
           root_of[u] = {sz(cycle) - 1, sz(cycle.back())};
-          cycle.back() += u;
+          cycle.back().push_back(u);
           state[u] = 2;
           u = a[u];
         }
       }
       int v = i;
       while (state[v] == 1) {
         root_of[v] = root_of[u];
-        childs[a[v]] += v;
+        childs[a[v]].push_back(v);
         state[v] = 2;
         v = a[v];
       }

library/graphs/strongly_connected_components/add_edges_strongly_connected.hpp

@@ -21,11 +21,11 @@ vector<pii> extra_edges(const auto& adj, int num_sccs,
   const vi& scc_id) {
   if (num_sccs == 1) return {};
   int n = sz(adj);
-  vector<basic_string<int>> scc_adj(num_sccs);
+  vector<vi> scc_adj(num_sccs);
   vector<bool> zero_in(num_sccs, 1);
   rep(i, 0, n) for (int u : adj[i]) {
     if (scc_id[i] == scc_id[u]) continue;
-    scc_adj[scc_id[i]] += scc_id[u];
+    scc_adj[scc_id[i]].push_back(scc_id[u]);
     zero_in[scc_id[u]] = 0;
   }
   vector<bool> vis(num_sccs);