bzoj 1269 [AHOI2006]文本编辑器editor

原题链接：http://www.lydsy.com/JudgeOnline/problem.php?id=1269

伸展树的运用，如下：

 

  1 #include<cstdio>
  2 #include<cstdlib>
  3 #include<cstring>
  4 #include<iostream>
  5 #include<algorithm>
  6 using std::swap;
  7 const int Max_N = 3000010;
  8 struct Node{
  9     char chr;
 10     int s;
 11     bool rev;
 12     Node *pre, *ch[2];
 13     inline void 
 14     set(char _chr = ' ', int _s = 0, Node *p = NULL){
 15         chr = _chr, s = _s, rev = 0;
 16         pre = ch[0] = ch[1] = p;
 17     }
 18     inline void push_up(){
 19         s = ch[0]->s + ch[1]->s + 1;
 20     }
 21     inline void update(){
 22         rev ^= 1;
 23         swap(ch[0], ch[1]);
 24     }
 25     inline void push_down(){
 26         if (rev != 0){
 27             rev ^= 1;
 28             ch[0]->update();
 29             ch[1]->update();
 30         }
 31     }
 32 };
 33 struct SplayTree{
 34     char buf[Max_N];
 35     Node *tail, *root, *null;
 36     Node stack[Max_N], *store[Max_N];
 37     int top, pos;
 38     void init(){
 39         top = 0, pos = 0;
 40         tail = &stack[0];
 41         null = tail++;
 42         null->set();
 43         root = newNode(' ');
 44         root->ch[1] = newNode(' ');
 45         root->ch[1]->pre = root;
 46         root->ch[1]->push_up();
 47         root->push_up();
 48     }
 49     inline Node *newNode(char chr){
 50         Node *p = null;
 51         if (!top) p = tail++;
 52         else p = store[--top];
 53         p->set(chr, 1, null);
 54         return p;
 55     }
 56     inline void rotate(Node *x, int c){
 57         Node *y = x->pre;
 58         y->push_down(), x->push_down();
 59         y->ch[!c] = x->ch[c];
 60         x->pre = y->pre;
 61         if (x->ch[c] != null) x->ch[c]->pre = y;
 62         if (y->pre != null) y->pre->ch[y->pre->ch[0] != y] = x;
 63         x->ch[c] = y;
 64         y->pre = x;
 65         y->push_up();
 66         if (y == root) root = x;
 67     }
 68     inline void splay(Node *x, Node *f){
 69         if (x == root) return;
 70         for (; x->pre != f; x->push_down()){
 71             if (x->pre->pre == f){
 72                 rotate(x, x->pre->ch[0] == x);
 73             } else {
 74                 Node *y = x->pre, *z = y->pre;
 75                 if (z->ch[0] == y){
 76                     if (y->ch[0] == x)
 77                         rotate(y, 1), rotate(x, 1);
 78                     else rotate(x, 0), rotate(x, 1);
 79                 } else {
 80                     if (y->ch[1] == x)
 81                         rotate(y, 0), rotate(x, 0);
 82                     else rotate(x, 1), rotate(x, 0);
 83                 }
 84             }
 85         }
 86         x->push_up();
 87     }
 88     inline Node *built(int l, int r){
 89         if (l > r) return null;
 90         int mid = (l + r) >> 1;
 91         Node *p = newNode(buf[mid]);
 92         p->ch[0] = built(l, mid - 1);
 93         if (p->ch[0] != null) p->ch[0]->pre = p;
 94         p->ch[1] = built(mid + 1, r);
 95         if (p->ch[1] != null) p->ch[1]->pre = p;
 96         p->push_up();
 97         return p;
 98     }
 99     inline void recycle(Node *x){
100         if (x != null){
101             recycle(x->ch[0]);
102             store[top++] = x;
103             recycle(x->ch[1]);
104         }
105     }
106     inline Node *select(Node *x, int k){
107         for (int t = 0; x != null;){
108             x->push_down();
109             t = x->ch[0]->s;
110             if (k == t + 1) break;
111             else if (k <= t) x = x->ch[0];
112             else k -= t + 1, x = x->ch[1];
113         }
114         return x;
115     }
116     inline void get_range(int x, int y){
117         splay(select(root, x + 1), null);
118         splay(select(root, y + 2), root);
119     }
120     inline void Gets(char *s){
121         char c;
122         while (c = getchar(), c != '\n') *s++ = c;
123         *s = '\0';
124     }
125     inline void insert(int n){
126         char c;
127         scanf("%c", &c);
128         Gets(buf + 1);
129         get_range(pos, pos);
130         Node *ret = built(1, n);
131         root->ch[1]->ch[0] = ret;
132         ret->pre = root->ch[1];
133         root->ch[1]->push_up();
134         root->push_up();
135     }
136     inline void del(int n){
137         get_range(pos, pos + n);
138         Node* &ret = root->ch[1];
139         ret->ch[0]->pre = null;
140 #ifdef LOCAL
141         recycle(ret->ch[0]);
142 #endif
143         ret->ch[0] = null;
144         ret->push_up();
145         root->push_up();
146     }
147     inline void rotate(int n){
148         get_range(pos, pos + n);
149         root->ch[1]->ch[0]->update();
150     }
151     inline  void get(){
152         splay(select(root, pos + 2), null);
153         printf("%c\n", root->chr);
154     }
155     inline void move(){
156         scanf("%d", &pos);
157     }
158     inline void prev(){
159         pos--;
160     }
161     inline void next(){
162         pos++;
163     }
164 }spt;
165 int main(){
166 #ifdef LOCAL
167     freopen("in.txt", "r", stdin);
168     freopen("out.txt", "w+", stdout);
169 #endif
170     spt.init();
171     int m, n;
172     char str[100];
173     scanf("%d", &m);
174     while (m--){
175         scanf("%s", str);
176         switch (str[0]){
177             case 'M':
178                 spt.move();
179                 break;
180             case 'I':
181                 scanf("%d", &n);
182                 spt.insert(n);
183                 break;
184             case 'D':
185                 scanf("%d", &n);
186                 spt.del(n);
187                 break;
188             case 'N':
189                 spt.next();
190                 break;
191             case 'P':
192                 spt.prev();
193                 break;
194             case 'R':
195                 scanf("%d", &n);
196                 spt.rotate(n);
197                 break;
198             case 'G':
199                 spt.get();
200                 break;
201         }
202     }
203     return 0;
204 }
View Code

 

posted @ 2015-05-01 09:42  GadyPu  阅读(177)  评论(0)  编辑  收藏  举报