NOI2003 文本编辑器

#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<string>

using namespace std;

void setIO(const string& a) {
freopen((a+".in").c_str(), "r", stdin);
freopen((a+".out").c_str(), "w", stdout);
}

struct Node* null;

const int N = 1024 * 1024 * 2+ 10;

struct Node {
char v;
int sz;
Node* ch[2];

Node(char v = 0) : v(v) {
ch[0] = ch[1] = null;
sz = 1;
}

void maintain() {
sz = ch[0]->sz + ch[1]->sz + 1;
}

int cmp(int k) const {
int s = ch[0]->sz + 1;
if(k == s) return -1;
return k < s ? 0 : 1;
}
}pool
, *pis = pool, *root;

void init() {
null = new(pis++) Node(0);
null->sz = 0;
null->ch[0] = null->ch[1] = null;
root = new(pis++) Node(-1);
root->ch[1] = new(pis++) Node(-1);
}

void rotate(Node*& o, int d) {
Node* t = o->ch[d];
o->ch[d] = t->ch[d^1];
t->ch[d^1] = o;
o->maintain();
(o = t)->maintain();
}

void splay(Node*& o, int k) {
int d = o->cmp(k);
if(d == -1) return;
if(d == 1) k -= o->ch[0]->sz + 1;
Node*& c = o->ch[d];
int d2 = c->cmp(k);
if(d2 != -1) {
if(d2 == 1) k -= c->ch[0]->sz + 1;
splay(c->ch[d2], k);
if(d == d2) rotate(o, d);
else rotate(c, d2);
}
rotate(o, d);
}

void split(Node*o, int k, Node*& l, Node*& r) {
splay(o, k);
l = o;
r = o->ch[1];
o->ch[1] = null;
o->maintain();
}

Node* merge(Node* l, Node* r) {
splay(l, l->sz);
l->ch[1] = r;
l->maintain();
return l;
}

void print(Node* o) {
if(o == null) return;
print(o->ch[0]);
if(0 < o->v) putchar(o->v);
print(o->ch[1]);
}

Node* newtree(const char s[], int l, int r) {
if(l > r) return null;
int mid = (l + r) >> 1;
Node* o = new(pis++) Node();
o->ch[0] = newtree(s, l, mid - 1);
o->v = s[mid];
o->ch[1] = newtree(s, mid + 1, r);
o->maintain();
return o;
}

char text
;

void insert(int pos, Node* o) {
Node *lft, *rgt;
split(root, pos, lft, rgt);
root = merge(lft, merge(o, rgt));
}

int main() {
#ifdef DEBUG
freopen("in.txt", "r", stdin);
//    freopen("out.txt", "w", stdout);
#endif

int m;
scanf("%d", &m);
init();

char opt[10], c;
int pos = 1, n, sz = 0;
Node *o, *lft, *rgt, *mid;

while(m--) {
scanf("%s", opt);
if(strcmp(opt, "Move") == 0) {
scanf("%d", &pos); ++pos;
}else if(strcmp(opt, "Insert") == 0) {
int n;
scanf("%d", &n);
for(int i = 0; i < n; i++) {
c = getchar();
while(c == '\n') c = getchar();
text[i] = c;
}
sz += n;
insert(pos, newtree(text, 0, n - 1));
}else if(strcmp(opt, "Delete") == 0) {
scanf("%d", &n);
n = min(sz - pos + 1, n);
split(root, pos, lft, o);
split(o, n, mid, rgt);
sz -= mid->sz;
root = merge(lft, rgt);
}else if(strcmp(opt, "Prev") == 0) {if(pos > 1) pos--;}
else if(strcmp(opt, "Next") == 0) {if(pos <= sz) pos++;}
else {
scanf("%d", &n);
split(root, pos, lft, o);
n = min(sz - pos + 1, n);
split(o, n, mid, rgt);
print(mid); puts("");
root = merge(merge(lft, mid), rgt);
}
}

return 0;
}