diff --git a/data_structure/segtree/nonrecursive.cpp b/data_structure/segtree/nonrecursive.cpp
new file mode 100644
index 0000000..ed173c6
--- /dev/null
+++ b/data_structure/segtree/nonrecursive.cpp
@@ -0,0 +1,26 @@
+template<typename T>
+struct segtree{
+    int sz, n;
+    vector<T> seg;
+    segtree(): sz(0) {}
+    segtree(int sz): sz(sz){seg.resize(2 * sz, 0LL);}
+    T& operator[](int idx){return seg[idx];}
+    void init(int n){
+        for (int i = 0; i < n; i++) cin >> seg[sz + i];
+        for (int i = sz - 1; i > 0; i--) seg[i] = seg[i << 1] + seg[i << 1 | 1];
+    }
+    void update(int pos, T val){
+        seg[sz + pos] = val;
+        for (pos += sz; pos > 1; pos >>= 1){
+            seg[pos >> 1] = seg[pos] + seg[pos ^ 1];
+        }
+    }
+    T query(int l, int r){
+        T ans = 0;
+        for (l += sz, r += sz; l <= r; l >>= 1, r >>= 1){
+            if (l&1) ans += seg[l++];
+            if (~r&1) ans += seg[r--];
+        }
+        return ans;
+    }
+};