add these back

Author: lrvideckis

library/trees/centroid_decomp.hpp

@@ -7,7 +7,7 @@
 //! @space O(n)
 void centroid(auto& g, auto f) {
   vi siz(sz(g));
-  auto ctd = [&](auto ctd, int u, int p, int n) {
+  auto ctd = [&](auto ctd, int u, int p, int n) -> int {
     siz[u] = 1;
     for (int v : g[u])
       if (v != p) {

library/trees/edge_cd.hpp

@@ -15,7 +15,7 @@
 //! @space O(n)
 template<class G> void edge_cd(vector<G>& g, auto f) {
   vi siz(sz(g));
-  auto ctd = [&](auto ctd, int u, int p, int m) {
+  auto ctd = [&](auto ctd, int u, int p, int m) -> int {
     siz[u] = 1;
     for (int v : g[u])
       if (v != p) {

library/trees/hld.hpp

@@ -14,7 +14,7 @@ template<bool VALS_EDGES> struct HLD {
   int n;
   vi p, siz, rt, tin;
   HLD(auto& g): n(sz(g)), p(n), siz(n, 1), rt(n), tin(n) {
-    auto dfs1 = [&](auto dfs1, int u) {
+    auto dfs1 = [&](auto dfs1, int u) -> void {
       for (int& v : g[u]) {
         erase(g[v], p[v] = u);
         dfs1(dfs1, v);
@@ -24,7 +24,7 @@ template<bool VALS_EDGES> struct HLD {
     };
     dfs1(dfs1, 0);
     int tim = 0;
-    auto dfs2 = [&](auto dfs2, int u) {
+    auto dfs2 = [&](auto dfs2, int u) -> void {
       tin[u] = tim++;
       for (int v : g[u]) {
         rt[v] = (v == g[u][0] ? rt[u] : v);

library/trees/lca_rmq.hpp

@@ -16,7 +16,7 @@ struct LCA {
   LCA(const auto& g):
     n(sz(g)), tin(n), siz(n, 1), d(n), p(n) {
     vi order;
-    auto dfs = [&](auto dfs, int u) {
+    auto dfs = [&](auto dfs, int u) -> void {
       tin[u] = sz(order), order.push_back(u);
       for (int v : g[u])
         if (v != p[u])

library/trees/linear_lca.hpp

@@ -13,7 +13,7 @@ struct linear_lca {
   linear_lca(const auto& g):
     n(sz(g)), d(n), in(n), asc(n), head(n + 1) {
     vector<pii> order;
-    auto dfs = [&](auto dfs, int u, int p) {
+    auto dfs = [&](auto dfs, int u, int p) -> void {
       order.emplace_back(u, p), in[u] = sz(order);
       for (int v : g[u])
         if (v != p) {

library/trees/shallowest_decomp_tree.hpp

@@ -9,7 +9,7 @@
 //! @space O(n)
 void shallowest(auto& g, auto f) {
   vector<vi> order(bit_width(size(g)));
-  auto dfs = [&](auto dfs, int u, int p) {
+  auto dfs = [&](auto dfs, int u, int p) -> int {
     int once = 0, twice = 0;
     for (int v : g[u])
       if (v != p) {

library/trees/tree_lift.hpp

@@ -11,7 +11,7 @@
 struct tree_lift {
   vi d, p, j;
   tree_lift(const auto& g): d(sz(g)), p(d), j(d) {
-    auto dfs = [&](auto dfs, int u) {
+    auto dfs = [&](auto dfs, int u) -> void {
       int up =
         d[u] + d[j[j[u]]] == 2 * d[j[u]] ? j[j[u]] : u;
       for (int v : g[u])

library/trees/uncommon/ladder_decomposition.hpp

@@ -17,7 +17,7 @@ struct ladder {
   //! @space O(n log n) for jmp. Everything else is O(n)
   ladder(const auto& g):
     n(sz(g)), d(n), p(n), leaf(n), idx(n), lad(2 * n) {
-    auto dfs = [&](auto dfs, int u) {
+    auto dfs = [&](auto dfs, int u) -> void {
       leaf[u] = u;
       for (int v : g[u])
         if (v != p[u]) {

library/trees/uncommon/subtree_isomorphism.hpp

@@ -12,7 +12,7 @@
 auto subtree_iso(const auto& g) {
   vi iso_id(sz(g), -1);
   map<vi, int> hashes;
-  auto dfs = [&](auto dfs, int u, int p) {
+  auto dfs = [&](auto dfs, int u, int p) -> int {
     vi ch_ids;
     for (int v : g[u])
       if (v != p) ch_ids.push_back(dfs(dfs, v, u));