diff --git a/src/8/18/segtreerange.cpp b/src/8/18/segtreerange.cpp
new file mode 100644
index 0000000..33909a3
--- /dev/null
+++ b/src/8/18/segtreerange.cpp
@@ -0,0 +1,86 @@
+#include <cstdint>
+#include <iostream>
+#include <vector>
+
+using ll = int64_t;
+
+ll n;
+std::vector<ll> t;
+std::vector<ll> v;
+std::vector<ll> lazy;
+
+ll create(ll cur,ll l,ll r){
+    if(l==r){
+        t[cur]=v[l];
+        return v[l];
+    }
+    ll mid = (l+r)/2;
+    t[cur]=create(2*cur, l, mid)
+        + create(2*cur+1, mid+1, r);
+    return t[cur];
+}
+
+
+ll rangeadd(ll cur, ll l, ll r, ll ql, ll qr, ll val) {
+    if (lazy[cur] != 0) {
+        t[cur] += lazy[cur] * (r - l + 1);
+        if (l != r) {
+            lazy[2 * cur] += lazy[cur];
+            lazy[2 * cur + 1] += lazy[cur];
+        }
+        lazy[cur] = 0;
+    }
+    if (ql > r || qr < l) return t[cur];
+    if (ql <= l && r <= qr) {
+        t[cur] += val * (r - l + 1);
+        if (l != r) {
+            lazy[2 * cur] += val;
+            lazy[2 * cur + 1] += val;
+        }
+        return t[cur];
+    }
+    ll mid = (l + r) / 2;
+    return t[cur] = rangeadd(2 * cur, l, mid, ql, qr, val)
+                   + rangeadd(2 * cur + 1, mid + 1, r, ql, qr, val);
+}
+
+ll rangequery(ll cur, ll l, ll r, ll ql, ll qr) {
+    if (lazy[cur] != 0) {
+        t[cur] += lazy[cur] * (r - l + 1);
+        if (l != r) {
+            lazy[2 * cur] += lazy[cur];
+            lazy[2 * cur + 1] += lazy[cur];
+        }
+        lazy[cur] = 0;
+    }
+    if (ql > r || qr < l) return 0;
+    if (ql <= l && r <= qr) return t[cur];
+    ll mid = (l + r) / 2;
+    return rangequery(2 * cur, l, mid, ql, qr)
+         + rangequery(2 * cur + 1, mid + 1, r, ql, qr);
+}
+
+int main(){
+    std::cin>>n;
+    t.resize((n+1)*4);
+    v.resize(n+1);
+    lazy.resize((n+1)*4);
+    for(ll i=1; i<=n; i++){
+        std::cin>>v[i];
+    }
+    create(1, 1, n);
+    ll q;
+    std::cin>>q;
+    while(q--){
+        ll l, r, val;
+        std::cin>>l>>r>>val;
+        rangeadd(1, 1, n, l, r, val);
+        std::cout << t[1] << "\n";
+    }
+    std::cin>>q;
+    while(q--){
+        ll l, r;
+        std::cin>>l>>r;
+        std::cout << rangequery(1, 1, n, l, r) << "\n";
+    }
+}
\ No newline at end of file
diff --git a/src/test.cpp b/src/test.cpp
index 3e2d2b5..c7d4a71 100644
--- a/src/test.cpp
+++ b/src/test.cpp
@@ -1,7 +1,64 @@
-#include <climits>
-#include <iostream>
-#include <random>
-int main(){
-    auto p = new int();
-    std::cout<<p<<'\n';
-}
\ No newline at end of file
+#include <list>
+class MyLinkedList {
+public:
+    std::list<int> l;
+    MyLinkedList() {
+        
+    }
+    
+    int get(int index) {
+        if(index>=l.size()){
+            return -1;
+        }
+        auto p = l.begin();
+        while(index--){
+            p++;
+        }
+        return *p;
+    }
+    
+    void addAtHead(int val) {
+        l.push_front(val);
+    }
+    
+    void addAtTail(int val) {
+        l.push_back(val);
+    }
+    
+    void addAtIndex(int index, int val) {
+        if(index==l.size()){
+            l.push_back(val);
+            return;
+        }
+        if(index>l.size())return;
+        auto p = l.begin();
+        while(index--){
+            ++p;
+        }
+        l.insert(p,val);
+    }   
+    
+    void deleteAtIndex(int index) {
+        if(0<=index && index<l.size()){
+            auto p = l.begin();
+            while(index--){
+                ++p;
+            }
+            l.erase(p);
+        }
+    }
+};
+
+/**
+ * Your MyLinkedList object will be instantiated and called as such:
+ * MyLinkedList* obj = new MyLinkedList();
+ * int param_1 = obj->get(index);
+ * obj->addAtHead(val);
+ * obj->addAtTail(val);
+ * obj->addAtIndex(index,val);
+ * obj->deleteAtIndex(index);
+ */
+
+ int main(){
+    
+ }
\ No newline at end of file