Splay初步【bzoj1503】
做了一道水题，把bzoj1503用Splay重新写了一下。
1 #include <bits/stdc++.h> 2 #define rep(i, a, b) for (int i = a; i <= b; i++) 3 #define REP(i, a, b) for (int i = a; i < b; i++) 4 #define drep(i, a, b) for (int i = a; i >= b; i--) 5 #define mp make_pair 6 #define pb push_back 7 #define clr(x) memset(x, 0, sizeof(x)) 8 #define xx first 9 #define yy second 10 using namespace std; 11 typedef long long i64; 12 typedef pair<int, int> pii; 13 const int inf = ~0U >> 1; 14 const i64 INF = ~0ULL >> 1; 15 //*************************** 16 17 struct node { 18 node *pre, *s[2]; 19 int key, size, mul; 20 node() { pre = s[0] = s[1] = 0; size = mul = 1; } 21 node(int _key) :key(_key) { pre = s[0] = s[1] = 0; size = mul = 1; } 22 bool getlr() { return pre->s[1] == this; } 23 node *link(int w, node *p) { s[w] = p; if (p) p->pre = this; return this; } 24 void update() { size = mul + (s[0] ? s[0]->size : 0) + (s[1] ? s[1]->size : 0); } 25 } *root; 26 void rot(node* p) { 27 node *q = p->pre->pre; 28 p->getlr() ? p->link(0, p->pre->link(1, p->s[0])) : p->link(1, p->pre->link(0, p->s[1])); 29 p->pre->update(); 30 if (q) q->link(q->s[1] == p->pre, p); 31 else { p->pre = 0; root = p; } 32 } 33 void splay(node *p, node *tar) { 34 while (p->pre != tar && p->pre->pre != tar) 35 p->getlr() == p->pre->getlr() ? (rot(p->pre), rot(p)) : (rot(p), rot(p)); 36 if (p->pre) rot(p); 37 p->update(); 38 } 39 void insrt(int k) { 40 node *p = root, *q = NULL; 41 while (p) { 42 q = p; 43 if (k > p->key) p = p->s[1]; 44 else if (k < p->key) p = p->s[0]; 45 else break; 46 } 47 if (!p) {p = new node(k); 48 if (!q) { root = p; return; } 49 q->link(q->key < k, p); q->update(); splay(p, 0); 50 } 51 else { p->mul++; splay(p, 0); } 52 } 53 node *findkth(int x) { 54 node *p = root; 55 node *t; 56 while (1) { 57 int w = (p->s[0] ? p->s[0]->size : 0); 58 if (x <= w) t = p->s[0]; 59 else if (x > w + p->mul) { x -= w + p->mul; t = p->s[1]; } 60 else break; 61 p = t; 62 } 63 splay(p, 0); return p; 64 } 65 66 node *find(node *p, int x) { 67 if (p->key < x) return find(p->s[1], x); 68 else if (p->key > x) return find(p->s[0], x); 69 else return p; 70 } 71 72 int main() { 73 int ori(0); 74 int n, m; 75 scanf("%d%d", &n, &m); 76 int tot(0); 77 char op[5]; int x; 78 while (n--) { 79 scanf("%s%d", op, &x); 80 if (op[0] == 'I') { 81 if (x >= m) { 82 ori++; 83 insrt(x - tot); 84 } 85 } 86 else if (op[0] == 'A') tot += x; 87 else if (op[0] == 'S') { 88 tot -= x; 89 insrt(m - tot - 1); 90 splay(find(root, m - tot - 1), 0); 91 root = root->s[1]; 92 if (root) root->pre = 0; 93 } 94 else if (op[0] == 'F') { 95 if (!root || x > root->size) puts("-1"); 96 else printf("%d\n", findkth(root->size - x + 1)->key + tot); 97 } 98 } 99 printf("%d\n", ori - (root ? root->size : 0)); 100 return 0; 101 }
