diff --git a/graph/hld.cc b/graph/hld.cc
new file mode 100644
index 0000000..28e4bed
--- /dev/null
+++ b/graph/hld.cc
@@ -0,0 +1,43 @@
+namespace HLD {
+    struct node_info {
+        int father, depth, hson, size, head, dfn = -1;
+    };
+
+    // returns: (dfs sequence, node info)
+    // node numbering starts from `1`
+    // if `dfn(v) == -1`, then node `v` is never accessed.
+    pair<vector<int>, vector<node_info>> work(int n, const vector<vector<int>>& ch, int root = 0) {
+        vector<int> seq;
+        vector<node_info> res(n + 1);
+        auto dfs1 = [&] (auto dfs1, int v, int pa) -> void {
+            res[v].father = pa;
+            res[v].depth = res[pa].depth + 1;
+            res[v].size = 1;
+            int mx = 0;
+            for (auto&& u : ch[v]) {
+                if (u == pa) continue;
+                dfs1(dfs1, u, v);
+                res[v].size += res[u].size;
+                if (res[u].size > mx) {
+                    mx = res[u].size;
+                    res[v].hson = u;
+                }
+            }
+        };
+        dfs1(dfs1, root, root);
+        int tm = 0;
+        auto dfs2 = [&] (auto dfs2, int v, int head) -> void {
+            res[v].dfn = tm++;
+            seq.emplace_back(v);
+            res[v].head = head;
+            if (not res[v].hson) return;
+            dfs2(dfs2, res[v].hson, head);
+            for (auto&& u : ch[v]) {
+                if (u == res[v].father or u == res[v].hson) continue;
+                dfs2(dfs2, u, u);
+            }
+        };
+        dfs2(dfs2, root, root);
+        return { seq, res };
+    }
+}