2488. 树套树-简单版

https://www.acwing.com/problem/content/submission/code_detail/15807446/

AcWing/2488/2488.cpp

@@ -0,0 +1,101 @@
+#include <iostream>
+#include <limits>
+#include <set>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 5e4 + 5;
+
+int n, m, a[N];
+
+struct node : public std::multiset<int> {
+    int l, r;
+
+    node()
+        : l(0), r(0) {}
+
+    node(int _l, int _r)
+        : l(_l), r(_r) {
+        insert(std::numeric_limits<int>::min());
+        insert(std::numeric_limits<int>::max());
+    }
+} tr[N << 2];
+
+void build(int u, int l, int r) {
+    tr[u] = node(l, r);
+
+    for (int i = l; i <= r; i++) {
+        tr[u].insert(a[i]);
+    }
+
+    if (l == r) return;
+
+    int mid = l + r >> 1;
+
+    build(u << 1, l, mid);
+    build(u << 1 | 1, mid + 1, r);
+}
+
+void modify(int u, int p, int x) {
+    tr[u].erase(tr[u].find(a[p]));
+    tr[u].insert(x);
+
+    if (tr[u].l == tr[u].r) return;
+
+    int mid = tr[u].l + tr[u].r >> 1;
+
+    if (p <= mid) modify(u << 1, p, x);
+    else modify(u << 1 | 1, p, x);
+}
+
+int query(int u, int l, int r, int x) {
+    if (l <= tr[u].l && tr[u].r <= r) {
+        return *--tr[u].lower_bound(x);
+    }
+
+    int mid = tr[u].l + tr[u].r >> 1;
+    int res = std::numeric_limits<int>::min();
+
+    if (l <= mid) res = std::max(res, query(u << 1, l, r, x));
+    if (r > mid) res = std::max(res, query(u << 1 | 1, l, r, x));
+
+    return res;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> m;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+    }
+
+    build(1, 1, n);
+
+    while (m--) {
+        int op;
+
+        cin >> op;
+
+        if (op == 1) {
+            int p, x;
+
+            cin >> p >> x;
+
+            modify(1, p, x);
+            a[p] = x;
+        } else {  // op == 2
+            int l, r, x;
+
+            cin >> l >> r >> x;
+
+            cout << query(1, l, r, x) << endl;
+        }
+    }
+
+    return 0;
+}