range queries and one graph

CSES - CSES Problem Set/Range_Queries/Dynamic_Range_Sum_Queries.cpp

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+//  Dynamic Range Sum Queries
+
+#include<bits/stdc++.h>
+using ll = long long;
+using namespace std;
+
+vector<ll> construct(vector<ll> &input) {
+    vector<ll> output(2 * input.size());
+    for (int i = 0; i < input.size(); i++) {
+        output[input.size() + i] = input[i];
+    }
+    for (int i = input.size() - 1; i > 0; i--) {
+        output[i] = output[2*i] + output[2*i + 1];
+    }
+    return output;
+}
+
+void update(int k, ll x, int n, vector<ll> &tree) {
+    k += n;
+    tree[k] = x;
+    k /= 2;
+    for (; k >= 1; k /= 2) {
+        tree[k] = tree[2*k + 1] + tree[2*k];
+    }
+}
+
+ll query(int a, int b, int n, vector<ll> &tree) {
+    a--; b--;
+    a += n; b += n;
+    ll s = 0;
+    while (a <= b) {
+        if (a % 2 == 1) {
+            s += tree[a];
+            a++;
+        }
+        if (b % 2 == 0) {
+            s += tree[b];
+            b--;
+        }
+        a /= 2; b /= 2;
+    }
+    return s;
+}
+
+int main() {
+    int n, q; cin >> n >> q;
+    vector<ll> in(n);
+    for (int i{}; i < n; i++) {
+        cin >> in[i];
+    }
+    auto seg = construct(in);
+    for (int i{}; i < q; i++) {
+        int t; cin >> t;
+        if (t == 2) {
+            int a, b; cin >> a >> b;
+            cout << query(a, b, n, seg) << endl;
+        } else if (t == 1) {
+            int k; ll u; cin >> k >> u;
+            k--;
+            update(k, u, n, seg);
+        }
+    }
+    return 0;
+}