Create dynamic.cpp

data_structure/segtree/dynamic.cpp

@@ -0,0 +1,29 @@
+//reference: https://justicehui.github.io/medium-algorithm/2020/02/28/DynamicSeg/
+struct Node{
+    Node *l, *r;
+    ll tsum;
+    Node(): l(nullptr), r(nullptr), tsum(0) {}
+};
+void update(Node *node, int s, int e, int p, ll val){
+    if (s == e){
+        node->tsum = val; return;
+    }
+    int m = (s + e) >> 1;
+    if (p <= m){
+        if (!node->l) node->l = new Node();
+        update(node->l, s, m, p, val);
+    }
+    else{
+        if (!node->r) node->r = new Node();
+        update(node->r, m + 1, e, p, val);
+    }
+    ll left_t = (node->l) ? node->l->tsum : 0;
+    ll right_t = (node->r) ? node->r->tsum : 0;
+    node->tsum = left_t + right_t;
+}
+ll query(Node *node, int s, int e, int le, int ri){
+    if (!node || ri < s || e < le) return 0;
+    if (le <= s && e <= ri) return node->tsum;
+    int m = (s + e) >> 1;
+    return query(node->l, s, m, le, ri) + query(node->r, m + 1, e, le, ri);
+}