NOI2003 文本编辑器

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#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 =  *  * + ; 

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

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

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

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

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

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

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

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

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

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

char text[N];

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[], c;
    int pos = , n, sz = ;
    Node *o, *lft, *rgt, *mid;

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

    return ;
}

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