diff --git a/Luogu/P2617/P2617.cpp b/Luogu/P2617/P2617.cpp
new file mode 100644
index 00000000..dfc9b19f
--- /dev/null
+++ b/Luogu/P2617/P2617.cpp
@@ -0,0 +1,126 @@
+#include <iostream>
+#include <cstring>
+#include <tuple>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1e5 + 5;
+
+int n, m, a[N], c[N], ans[N];
+
+inline int lowbit(int x) {
+    return x & -x;
+}
+
+inline void add(int x, int y) {
+    for (; x <= n; x += lowbit(x)) c[x] += y;
+}
+
+inline int sum(int x) {
+    int ret = 0;
+    for (; x > 0; x -= lowbit(x)) ret += c[x];
+    return ret;
+}
+
+void solve(int l, int r, const std::vector<std::tuple<char, int, int, int, int>>& q) {
+    if (q.empty()) return;
+
+    if (r - l == 1) {
+        for (const auto& x : q) {
+            if (std::get<0>(x) == 'Q') {
+                ans[std::get<4>(x)] = l;
+            }
+        }
+
+        return;
+    }
+
+    int mid = l + r >> 1;
+    std::vector<std::tuple<char, int, int, int, int>> left, right;
+
+    for (const auto& e : q) {
+        char op;
+        int x, y, z, id;
+
+        std::tie(op, x, y, z, id) = e;
+
+        if (op == 'Q') {
+            int k = sum(y) - sum(x - 1);
+
+            if (k >= z) {
+                left.push_back(e);
+            } else {
+                z -= k;
+                right.emplace_back(op, x, y, z, id);
+            }
+        } else {  // op == 'C'
+            if (y < mid) {
+                add(x, z);
+                left.push_back(e);
+            } else {
+                right.push_back(e);
+            }
+        }
+    }
+
+    for (const auto& e : left) {
+        char op;
+        int x, y, z, id;
+
+        std::tie(op, x, y, z, id) = e;
+
+        if (op == 'C') {
+            add(x, -z);
+        }
+    }
+
+    solve(l, mid, left);
+    solve(mid, r, right);
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    memset(ans, 0xff, sizeof(ans));
+
+    cin >> n >> m;
+
+    std::vector<std::tuple<char, int, int, int, int>> q;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+
+        q.emplace_back('C', i, a[i], 1, 0);
+    }
+
+    for (int i = 1; i <= m; i++) {
+        char op;
+        int x, y, z;
+
+        cin >> op >> x >> y;
+
+        if (op == 'Q') {
+            cin >> z;
+
+            q.emplace_back('Q', x, y, z, i);
+        } else {  // op == 'C'
+            q.emplace_back('C', x, a[x], -1, 0);
+            a[x] = y;
+            q.emplace_back('C', x, y, 1, 0);
+        }
+    }
+
+    solve(0, 1e9, q);
+
+    for (int i = 1; i <= m; i++) {
+        if (~ans[i]) {
+            cout << ans[i] << endl;
+        }
+    }
+
+    return 0;
+}