B - Fenwick Tree

https://atcoder.jp/contests/practice2/submissions/33500324

AtCoder/practice2/B/B.cpp

@@ -0,0 +1,40 @@
+#include <iostream>
+#include <atcoder/fenwicktree>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, q;
+
+    cin >> n >> q;
+
+    atcoder::fenwick_tree<long long> tr(n);
+
+    for (int i = 0; i < n; i++) {
+        long long x;
+
+        cin >> x;
+
+        tr.add(i, x);
+    }
+
+    while (q--) {
+        int op;
+        long long x, y;
+
+        cin >> op >> x >> y;
+
+        if (op == 0) {
+            tr.add(x, y);
+        } else {  // op == 1
+            cout << tr.sum(x, y) << endl;
+        }
+    }
+
+    return 0;
+}