HDU 3487：Play with Chain（Splay）

http://acm.hdu.edu.cn/showproblem.php?pid=3487

题意：有两种操作：1、Flip l r ，把 l 到 r 这段区间 reverse。2、Cut a b c ，把 a 到 b 这段区间切掉，再把这段区间接到切掉后的第 c 个数的后面。

思路：做完了上一道变态题目，做这道题目如鱼得水。Cut的时候就是把a 到 b 放到keytree的位置，记录一下当前keytree的值，然后切掉，再把切掉后的第 c 个数转到 root 的位置，再把这个记录的值重新连接回去。要注意当全部询问结束了，要把所有的rev标记pushdown。

 #include <cstdio>
 #include <cstring>
 #include <cmath>
 #include <cstdlib>
 #include <algorithm>
 #include <string>
 #include <iostream>
 #include <stack>
 #include <map>
 #include <queue>
 using namespace std;
 #define N 300100
 #define INF 0x3f3f3f3f
 #define lson ch[x][0]
 #define rson ch[x][1]
 #define keytree ch[ch[root][1]][0]

 struct SplayTree
 {
     int num[N], rev[N], ch[N][], fa[N], val[N], sz[N];
     int n, root, cnt, ans[N], tol;

     void PushDown(int x)
     {
         if(rev[x]) {
             swap(lson, rson);
             if(lson) rev[lson] ^= ;
             if(rson) rev[rson] ^= ;
             rev[x] = ;
         }
     }

     void PushUp(int x)
     {
         sz[x] = sz[lson] + sz[rson] + ;
     }

     int NewNode(int w, int f, int kind)
     {
         int x = ++cnt;
         ch[x][] = ch[x][] = rev[x] = ;
         sz[x] = ; val[x] = w; fa[x] = f;
         ch[f][kind] = cnt;
         return x;
     }

     void Build(int l, int r, int &x, int f, int kind)
     {
         if(l > r) return ;
         int m = (l + r) >> ;
         x = NewNode(num[m], f, kind);
         Build(l, m - , ch[x][], x, );
         Build(m + , r, ch[x][], x, );
         PushUp(x);
     }

     void Init()
     {
         root = cnt = tol = ;
         rev[] = val[] = fa[] = sz[] = ch[][] = ch[][] = ;
         root = NewNode(, , );
         ch[root][] = NewNode(, root, );
         sz[root] = ;
         Build(, n, keytree, ch[root][], );
         PushUp(ch[root][]); PushUp(root);
     }

     void Rotate(int x, int kind)
     {
         int y = fa[x], z = fa[y];
         PushDown(y); PushDown(x);
         ch[y][!kind] = ch[x][kind];
         if(ch[y][!kind]) fa[ch[y][!kind]] = y;
         if(z) {
             if(y == ch[z][]) ch[z][] = x;
             else ch[z][] = x;
         }
         fa[x] = z; fa[y] = x;
         ch[x][kind] = y;
         PushUp(y);
     }

     void Splay(int x, int goal)
     {
         while(fa[x] != goal) {
             int y = fa[x], z = fa[y];
             PushDown(z); PushDown(y); PushDown(x);
             int kind1 = x == ch[y][];
             int kind2 = y == ch[z][];
             if(z == goal) {
                 Rotate(x, kind1);
             } else {
                 if(kind1 == kind2) {
                     Rotate(y, kind1);
                 } else {
                     Rotate(x, kind1);
                 }
                 Rotate(x, kind2);
             }
         }
         PushUp(x);
         if(goal == ) root = x;
     }

     void RTO(int k, int goal)
     {
         int x = root;
         PushDown(x);
         while(k != sz[lson] + ) {
             if(k <= sz[lson]) x = lson;
             else k -= sz[lson] + , x = rson;
             PushDown(x);
         }
         Splay(x, goal);
     }

     void Cut(int l, int r, int c)
     {
         RTO(l, );
 //        Debug();
         RTO(r + , root);
         int tmp = keytree;
         keytree = ;
 //        Debug();
         RTO(c + , );
 //        Debug();
         RTO(c + , root);
         fa[tmp] = ch[root][];
         keytree = tmp;
     }

     void Reverse(int l, int r)
     {
         RTO(l, ); RTO(r + , root);
         rev[keytree] ^= ;
     }

     void Down(int x)
     {
         PushDown(x);
         if(lson) Down(lson);
         if(rson) Down(rson);
     }

     void Travel(int x)
     {
         if(lson) Travel(lson);
         ans[tol++] = val[x];
         if(rson) Travel(rson);
     }

     void Debug()
     {
         Down(root);
         Travel(root);
         for(int i = ; i <= n; i++) {
             if(i == n) printf("%d\n", ans[i]);
             else printf("%d ", ans[i]);
         }
     }
 }spy;

 int main()
 {
     int n, m;
     while(scanf("%d%d", &n, &m)) {
         if(n <  || m < ) break;
         spy.n = n;
         for(int i = ; i <= n; i++) spy.num[i] = i;
         spy.Init();
         while(m--) {
             char s[];
             int a, b, c;
             scanf("%s", s);
             if(s[] == 'C') {
                 scanf("%d%d%d", &a, &b, &c);
                 spy.Cut(a, b, c);
             } else {
                 scanf("%d%d", &a, &b);
                 spy.Reverse(a, b);
             }
         }
         spy.Debug();
     }
     return ;
 }