feat(cses): range queries

;

cses/range-queries/dynamic-range-sum-queries.cc

@@ -0,0 +1,164 @@
+#include <bits/stdc++.h>  // {{{
+
+// https://codeforces.com/blog/entry/96344
+
+#pragma GCC optimize("O2,unroll-loops")
+#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
+
+using namespace std;
+
+template <typename T>
+constexpr T MIN = std::numeric_limits<T>::min();
+
+template <typename T>
+constexpr T MAX = std::numeric_limits<T>::max();
+
+template <typename T>
+[[nodiscard]] static T sc(auto&& x) {
+  return static_cast<T>(x);
+}
+
+template <typename T>
+[[nodiscard]] static T sz(auto&& x) {
+  return static_cast<T>(x.size());
+}
+
+#define prln(...) std::println(__VA_ARGS__)
+#define pr(...) std::print(__VA_ARGS__)
+
+#ifdef LOCAL
+#define dbgln(...) std::println(__VA_ARGS__)
+#define dbg(...) std::print(__VA_ARGS__)
+#endif
+
+using ll = long long;
+using ld = long double;
+template <typename T>
+using v = std::vector<T>;
+template <typename T, size_t N>
+using r = std::array<T, N>;
+template <typename T1, typename T2>
+using p = std::pair<T1, T2>;
+
+#define ff first
+#define ss second
+#define eb emplace_back
+#define pb push_back
+#define all(x) (x).begin(), (x).end()
+#define rall(x) (x).rbegin(), (x).rend()
+//  }}}
+
+template <typename T>
+struct fenwick_tree {
+ public:
+  explicit fenwick_tree(std::vector<T> const& ts) : tree(ts.size()) {
+    for (size_t i = 0; i < ts.size(); ++i) {
+      tree[i] = ts[i];
+    }
+    for (size_t i = 0; i < tree.size(); ++i) {
+      size_t j = g(i);
+      if (j < tree.size()) {
+        tree[j] += tree[i];
+      }
+    }
+  }
+
+  T const query(int i) const {
+    if (!(0 <= i && i < static_cast<int>(tree.size()))) {
+      return T();
+    }
+
+    T t = sentinel();
+
+    for (int j = static_cast<int>(i); j >= 0; j = h(j) - 1) {
+      t = merge(t, tree[j]);
+    }
+
+    return t;
+  };
+
+  T const query(int l, int r) const {
+    if (!(0 <= l && r < static_cast<int>(tree.size()))) {
+      return T();
+    }
+
+    if (l == 0) {
+      return query(r);
+    }
+
+    return unmerge(query(r), query(l - 1));
+  };
+
+  void update(int i, T const& t) noexcept {
+    assert(0 <= i && i < static_cast<int>(tree.size()));
+
+    for (size_t j = i; j < tree.size(); j = g(j)) {
+      tree[j] = merge(tree[j], t);
+    }
+  }
+
+ private:
+  [[nodiscard]] inline T merge(T const& x, T const& y) const noexcept {
+    return x + y;
+  }
+
+  [[nodiscard]] inline T unmerge(T const& x, T const& y) const noexcept {
+    return x - y;
+  }
+
+  [[nodiscard]] inline T sentinel() const noexcept {
+    return 0;
+  }
+
+  [[nodiscard]] inline size_t g(size_t i) const noexcept {
+    return i | (i + 1);
+  }
+
+  [[nodiscard]] inline size_t h(size_t i) const noexcept {
+    return i & (i + 1);
+  }
+
+  std::vector<T> tree;
+};
+
+void solve() {
+  int n, q;
+  cin >> n >> q;
+
+  v<ll> a(n);
+  for (auto& e : a)
+    cin >> e;
+
+  fenwick_tree<ll> fw(a);
+  while (q--) {
+    char cmd;
+    cin >> cmd;
+    if (cmd == '1') {
+      int i;
+      ll u;
+      cin >> i >> u;
+      --i;
+      fw.update(i, u - a[i]);
+      a[i] = u;
+    } else {
+      int l, r;
+      cin >> l >> r;
+      --l;
+      --r;
+      cout << fw.query(l, r) << endl;
+    }
+  }
+}
+
+int main() {  // {{{
+  cin.tie(nullptr)->sync_with_stdio(false);
+
+  int t = 1;
+  // cin >> t;
+  while (t--) {
+    solve();
+  }
+
+  return 0;
+}
+// }}}