950. 郁闷的出纳员

https://www.acwing.com/problem/content/submission/code_detail/16213761/

AcWing/950/950.cpp

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+#include <iostream>
+
+using std::cin;
+using std::cout;
+using std::endl;
+
+const int N = 1e5 + 5;
+
+int n, min, k, c, ans;
+char op;
+
+// Treap
+
+int root, cnt;
+
+struct node {
+    int l, r, s, v, k;
+
+    node()
+        : l(0), r(0), s(0), v(0), k(rand()) {}
+
+    node(int _v)
+        : l(0), r(0), s(1), v(_v), k(rand()) {}
+} tr[N];
+
+void pushup(int u) {
+    tr[u].s = tr[tr[u].l].s + 1 + tr[tr[u].r].s;
+}
+
+std::pair<int, int> split(int p, int k) {
+    if (!p)
+        return std::make_pair(0, 0);
+
+    if (k <= tr[tr[p].l].s) {
+        auto o = split(tr[p].l, k);
+        tr[p].l = o.second;
+        pushup(p);
+        o.second = p;
+        return o;
+    }
+
+    auto o = split(tr[p].r, k - tr[tr[p].l].s - 1);
+    tr[p].r = o.first;
+    pushup(p);
+    o.first = p;
+
+    return o;
+}
+
+std::pair<int, int> splitByValue(int p, int v) {
+    if (!p)
+        return std::make_pair(0, 0);
+
+    if (v <= tr[p].v) {
+        auto o = splitByValue(tr[p].l, v);
+        tr[p].l = o.second;
+        pushup(p);
+        o.second = p;
+        return o;
+    }
+
+    auto o = splitByValue(tr[p].r, v);
+    tr[p].r = o.first;
+    pushup(p);
+    o.first = p;
+
+    return o;
+}
+
+int merge(int x, int y) {
+    if (!x || !y)
+        return x | y;
+
+    if (tr[x].k > tr[y].k) {
+        tr[x].r = merge(tr[x].r, y);
+        pushup(x);
+        return x;
+    }
+
+    tr[y].l = merge(x, tr[y].l);
+    pushup(y);
+
+    return y;
+}
+
+void insert(int v) {
+    auto o = splitByValue(root, v);
+    int p = ++cnt;
+
+    tr[p] = node(v);
+
+    root = merge(o.first, merge(p, o.second));
+}
+
+int getKth(int k) {
+    auto x = split(root, k - 1);
+    auto y = split(x.second, 1);
+
+    int r = y.first;
+
+    root = merge(x.first, merge(y.first, y.second));
+
+    return tr[r].v;
+}
+
+int main() {
+    cin >> n >> min;
+
+    while (n--) {
+        cin >> op >> k;
+
+        if (op == 'I') {
+            if (k >= min) {
+                insert(k - c);
+            }
+        } else if (op == 'A') {
+            c += k;
+        } else if (op == 'S') {
+            c -= k;
+            auto o = splitByValue(root, min - c);
+            root = o.second;
+            ans += tr[o.first].s;
+        } else {  // op == 'F'
+            cout << (tr[root].s < k ? -1 : getKth(tr[root].s - k + 1) + c) << endl;
+        }
+    }
+
+    cout << ans << endl;
+
+    return 0;
+}