【HYSBZ】1503 郁闷的出纳员

#include<cstdio>
#define INF 0x7FFFFFFF
#define MAXN 100010
struct SplayTree {
    int num[MAXN], next[MAXN][2], pre[MAXN], key[MAXN];
    int root, size;
    inline void PushUp(int x) {
        num[x] = num[next[x][0]] + num[next[x][1]] + 1;
    }
    inline void Rotate(int x, int kind) {
        int y, z;
        y = pre[x];
        z = pre[y];
        next[y][!kind] = next[x][kind];
        pre[next[x][kind]] = y;
        next[z][next[z][1] == y] = x;
        pre[x] = z;
        next[x][kind] = y;
        pre[y] = x;
        PushUp(y);
        PushUp(x);
    }
    void Splay(int x, int goal) {
        if (x != goal) {
            while (pre[x] != goal) {
                if (next[pre[x]][0] == x)
                    Rotate(x, 1);
                else
                    Rotate(x, 0);
            }
            if (!goal)
                root = x;
        }
    }
    inline void NewNode(int &x, int y, int val) {
        x = ++size;
        num[x] = 1;
        pre[x] = y;
        next[x][0] = next[x][1] = 0;
        key[x] = val;
        next[y][val > key[y]] = x;
    }
    void Insert(int val) {
        int x, y;
        for (x = root, y = 0; x; x = next[x][val > key[x]]) {
            y = x;
            num[x]++;
        }
        NewNode(x, y, val);
        Splay(x, 0);
    }
    int Search(int val) {
        int res, x;
        for (res = 0, x = root; x; x = next[x][val > key[x]]) {
            if (key[x] >= val && key[res] >= key[x])
                res = x;
        }
        return res;
    }
    int Select(int k) {
        int x;
        k = num[root] - k;
        for (x = root; num[next[x][0]] + 1 != k;) {
            if (num[next[x][0]] + 1 < k) {
                k -= num[next[x][0]] + 1;
                x = next[x][1];
            } else
                x = next[x][0];
        }
        Splay(x, 0);
        return key[x];
    }
    inline void Init() {
        root = size = 0;
        num[0] = next[0][0] = next[0][1] = pre[0];
        key[0] = INF;
        Insert(INF);
    }
} tree;
int main() {
    char ch;
    int q, base, diff, ans, x;
    while (~scanf("%d%d", &q, &base)) {
        tree.Init();
        diff = ans = 0;
        while (q--) {
            scanf(" %c%d", &ch, &x);
            if (ch == 'I') {
                if (x >= base)
                    tree.Insert(x - base + diff);
            } else if (ch == 'A')
                diff -= x;
            else if (ch == 'S') {
                diff += x;
                tree.Splay(tree.Search(diff), 0);
                ans += tree.num[tree.next[tree.root][0]];
                tree.num[tree.root] -= tree.num[tree.next[tree.root][0]];
                tree.next[tree.root][0] = 0;
            } else {
                if (x >= tree.num[tree.root])
                    puts("-1");
                else
                    printf("%d\n", tree.Select(x) + base - diff);
            }
        }
        printf("%d\n", ans);
    }
    return 0;
}