BZOJ1269——[AHOI2006]文本编辑器editor

1、题意：各种splay操作，一道好的模板题2333

2、分析：splay模板题，没啥解释QAQ

#include <stack> #include <cstdio>#include <cstdlib>#include <cstring>#include <algorithm>using namespace std;#define M 2000010 inline int read(){    char ch = getchar(); int x = 0, f = 1;    while(ch < '0' || ch > '9'){        if(ch == '-') f = -1;        ch = getchar();    }    while('0' <= ch && ch <= '9'){        x = x * 10 + ch - '0';        ch = getchar();    }    return x * f;} namespace splay{    struct Node{        Node *ch[2], *fa;        char c;        bool rev;        int size;                 inline int which();                 inline void reverse(){            rev ^= 1;            swap(ch[0], ch[1]);        }                  inline void pd(){            if(rev){                ch[0] -> reverse();                ch[1] -> reverse();                rev = false;             }        }                 inline void maintain(){            size = 1 + ch[0] -> size + ch[1] -> size;        }                 Node();    } *null = new Node, ft[M];         int tot;         Node::Node(){        size = 1;        c = '\0';        ch[0] = ch[1] = fa = null;        rev = false;    }          inline int Node::which(){        if(fa == null) return -1;        return this == fa -> ch[1];    }         inline void rotate(Node *o){        Node *p = o -> fa;        int l = o -> which(), r = l ^ 1;        o -> fa = p -> fa;        if(p -> which() != -1) p -> fa -> ch[p -> which()] = o;        p -> ch[l] = o -> ch[r];        if(o -> ch[r]) o -> ch[r] -> fa = p;        o -> ch[r] = p; p -> fa = o;        o -> ch[r] -> maintain();        o -> maintain();    }         inline void splay(Node *o){        static stack<Node*> st;        if(!o) return;        Node *p = o;        while(1){            st.push(p);            if(p -> which() == -1) break;            p = p -> fa;        }        while(!st.empty()){            st.top() -> pd();            st.pop();        }        while(o -> which() != -1){            p = o -> fa;            if(p -> which() != -1){                if(p -> which() ^ o -> which()) rotate(o);                else rotate(p);            }            rotate(o);        }    }         inline Node* Kth(Node *o, int k){        o -> pd();         int t = o -> ch[0] -> size + 1;        if(k == t) return o;        if(k < t) return Kth(o -> ch[0], k);        return Kth(o -> ch[1], k - t);    }         inline Node *merge(Node *a, Node *b){        if(a == null) return b;        if(b == null) return a;        Node *p = Kth(a, a -> size);        splay(p);        Node *c = p;        c -> ch[1] = b;        b -> fa = c;        c -> maintain();        return c;    }         inline void split(Node *o, int k, Node* &a, Node* &b){        if(k == 0){            a = null;            b = o;            return;        }        if(k == o -> size){            a = o;            b = null;            return;        }        Node *p = Kth(o, k);        splay(p);        o = p;        o -> maintain();        b = p -> ch[1];        b -> fa = null;        p -> ch[1] = null;        a = p;        a -> maintain();    }}  using namespace splay; int main(){    null -> ch[0] = null -> ch[1] = null -> fa = null;    null -> c = '\0'; null -> rev = false; null -> size = 0;    int n = read(); int now = 0;    Node *root = null;     char str[10];     for(int i = 1; i <= n; i ++){        scanf("%s", str);        if(str[0] == 'M'){            int x = read(); now = x;        }         else if(str[0] == 'I'){            int x = read();            Node *a, *b, *d = null;            split(root, now, a, b);            for(int i = 1; i <= x; i ++){                char ch = getchar();                Node *c = &ft[++ tot];                c -> c = ch;                d = merge(d, c);            }            root = merge(a, d);            root = merge(root, b);        }        else if(str[0] == 'D'){            int x = read();            Node *a, *b, *c;            split(root, now, a, b);            split(b, x, b, c);            root = merge(a, c);        }        else if(str[0] == 'R'){            int x = read();            Node *a, *b, *c;            split(root, now, a, b);            split(b, x, b, c);            b -> reverse();            root = merge(a, b);            root = merge(root, c);        }        else if(str[0] == 'G'){            Node *p = Kth(root, now + 1);            printf("%c\n", p -> c);        }        else if(str[0] == 'P'){            now --;        }        else{            now ++;        }    }    return 0;}