diff --git a/trees/odt.cc b/trees/odt.cc
new file mode 100644
index 0000000..afcffd5
--- /dev/null
+++ b/trees/odt.cc
@@ -0,0 +1,49 @@
+template <typename T, typename IndexType = ll>
+struct ODT {
+    struct Info {
+        IndexType l, r;
+        mutable T val;
+        Info(const IndexType& l, const IndexType& r, const T& val) : l(l), r(r), val(val) {}
+        friend inline bool operator<(const Info& lhs, const Info& rhs) { return lhs.l < rhs.l; }
+    };
+
+    set<Info> info;
+
+    ODT() = delete;
+    ODT(const IndexType& left, const IndexType& right, const T& val) : info {{ left, right, val }} {}
+
+    typename set<Info>::iterator split(const IndexType& x) {
+        auto it = info.lower_bound({ x, {}, {} });
+        if (it != info.end() and it->l == x) {
+            return it;
+        }
+        --it;
+        auto [l, r, val] = *it;
+        info.erase(it);
+        info.emplace(l, x - 1, val);
+        return info.emplace(x, r, val).first;
+    }
+
+    void assign(const IndexType& l, const IndexType& r, const T& val) {
+        auto ri = split(r + 1), li = split(l);
+        info.erase(li, ri);
+        info.emplace(l, r, val);
+    }
+
+    void transform(const IndexType& l, const IndexType& r, const function<T(const Info&)>& operation) {
+        auto ri = split(r + 1), li = split(l);
+        for (; li != ri; ++li) {
+            li->val = operation(*li);
+        }
+    }
+
+    template <typename U>
+    U accumulate(const IndexType& l, const IndexType& r, U&& init, const function<U(const U&, const Info&)>& operation = std::plus()) {
+        auto ri = split(r + 1), li = split(l);
+        U res = init;
+        for (; li != ri; ++li) {
+            res = operation(res, *li);
+        }
+        return res;
+    }
+};