Splay初步【bzoj1503】

做了一道水题，把bzoj1503用Splay重新写了一下。

 #include <bits/stdc++.h>
 #define rep(i, a, b) for (int i = a; i <= b; i++)
 #define REP(i, a, b) for (int i = a; i < b; i++)
 #define drep(i, a, b) for (int i = a; i >= b; i--)
 #define mp make_pair
 #define pb push_back
 #define clr(x) memset(x, 0, sizeof(x))
 #define xx first
 #define yy second
 using namespace std;
 typedef long long i64;
 typedef pair<int, int> pii;
 const int inf = ~0U >> ;
 const i64 INF = ~0ULL >> ;
 //***************************

 struct node {
     node *pre, *s[];
     int key, size, mul;
     node() { pre = s[] = s[] = ; size = mul = ; }
     node(int _key) :key(_key) { pre = s[] = s[] = ; size = mul = ; }
     bool getlr() { return pre->s[] == this; }
     node *link(int w, node *p) { s[w] = p; if (p) p->pre = this; return this; }
     void update() { size = mul + (s[] ? s[]->size : ) + (s[] ? s[]->size : ); }
 } *root;
 void rot(node* p) {
     node *q = p->pre->pre;
     p->getlr() ? p->link(, p->pre->link(, p->s[])) : p->link(, p->pre->link(, p->s[]));
     p->pre->update();
     if (q) q->link(q->s[] == p->pre, p);
     else { p->pre = ; root = p; }
 }
 void splay(node *p, node *tar) {
     while (p->pre != tar && p->pre->pre != tar)
         p->getlr() == p->pre->getlr() ? (rot(p->pre), rot(p)) : (rot(p), rot(p));
     if (p->pre) rot(p);
     p->update();
 }
 void insrt(int k) {
     node *p = root, *q = NULL;
     while (p) {
         q = p;
         if (k > p->key) p = p->s[];
         else if (k < p->key) p = p->s[];
         else break;
     }
     if (!p) {p = new node(k);
         if (!q) { root = p; return; }
         q->link(q->key < k, p); q->update(); splay(p, );
     }
     else { p->mul++; splay(p, ); }
 }
 node *findkth(int x) {
     node *p = root;
     node *t;
     while () {
         int w = (p->s[] ? p->s[]->size : );
         if (x <= w) t = p->s[];
         else if (x > w + p->mul) { x -= w + p->mul; t = p->s[]; }
         else break;
         p = t;
     }
     splay(p, ); return p;
 }

 node *find(node *p, int x) {
     if (p->key < x) return find(p->s[], x);
     else if (p->key > x) return find(p->s[], x);
     else return p;
 }

 int main() {
     int ori();
     int n, m;
     scanf("%d%d", &n, &m);
     int tot();
     char op[]; int x;
     while (n--) {
         scanf("%s%d", op, &x);
         if (op[] == 'I') {
             if (x >= m) {
                 ori++;
                 insrt(x - tot);
             }
         }
         else if (op[] == 'A') tot += x;
         else if (op[] == 'S') {
             tot -= x;
             insrt(m - tot - );
             splay(find(root, m - tot - ), );
             root = root->s[];
             if (root) root->pre = ;
         }
         else if (op[] == 'F') {
             if (!root || x > root->size) puts("-1");
             else printf("%d\n", findkth(root->size - x + )->key + tot);
         }
     }
     printf("%d\n", ori - (root ? root->size : ));
     return ;
 }