diff --git a/string/hash_vec.cc b/string/hash_vec.cc
new file mode 100644
index 0000000..7ebc782
--- /dev/null
+++ b/string/hash_vec.cc
@@ -0,0 +1,69 @@
+static vector<MLL<MDL1>> power1;
+static vector<MLL<MDL2>> power2;
+static const ll b = rd();
+template <typename _Tp>
+struct hash_vec {
+    using hash_type = pll;
+    MLL<MDL1> hash1;
+    MLL<MDL2> hash2;
+    vector<_Tp> seq;
+    size_t size() {
+        return seq.size();
+    }
+    void push_back(const _Tp& x) {
+        hash1 = hash1 * b + x;
+        hash2 = hash2 * b + x;
+        seq.push_back(x);
+    }
+    void push_front(const _Tp& x) {
+        size_t length = size();
+        hash1 += x * power1[length];
+        hash2 += x * power2[length];
+        seq.push_front(x);
+    }
+    void pop_back() {
+        _Tp e = seq.back(); seq.pop_back();
+        hash1 = (hash1 - e) / b;
+        hash2 = (hash2 - e) / b;
+    }
+    void pop_front() {
+        _Tp e = seq.front(); seq.pop_front();
+        int length = seq.size();
+        hash1 -= e * power1[length];
+        hash2 -= e * power2[length];
+    }
+    void set(size_t pos, const _Tp& value) {
+        int length = seq.size();
+        int old_value = seq[pos];
+        hash1 += (value - old_value) * power1[length - 1 - pos];
+        hash2 += (value - old_value) * power2[length - 1 - pos];
+        seq[pos] = value;
+    }
+    const _Tp& operator[](size_t pos) {
+        return seq[pos];
+    }
+    hash_type hash() {
+        return {hash1.val, hash2.val};
+    }
+    void clear() {
+        hash1 = 0;
+        hash2 = 0;
+        seq.clear();
+    }
+    hash_vec(size_t maxn) {
+        clear();
+        MLL<MDL1> c1 = 1;
+        MLL<MDL2> c2 = 1;
+        for (int i = power1.size(); i < maxn; ++i) {
+            power1.push_back(c1);
+            power2.push_back(c2);
+            c1 *= b;
+            c2 *= b;
+        }
+    }
+    hash_vec(size_t maxn, const _Tp& init_value) : hash_vec(maxn) {
+        for (size_t i = 0; i != maxn; ++i) {
+            push_back(init_value);
+        }
+    }
+};