[codevs4655] 序列终结者（Splay）

传送门

支持操作：

1.区间加

2.区间翻转

3.区间求最大值

splay模板

注意：update 里更新 max 时需要取 3 个值的 Max

　　　别忘了各种边界讨论

——代码

 #include <cstdio>
 #define ls son[now][0]
 #define rs son[now][1]

 const int MAXN = , INF = 2e9;
 int n, m, root, cnt;
 int a[MAXN], size[MAXN], key[MAXN], add[MAXN], max[MAXN], rev[MAXN], f[MAXN], son[MAXN][];

 inline void swap(int &x, int &y)
 {
     x ^= y ^= x ^= y;
 }

 inline int Max(int x, int y)
 {
     return x > y ? x : y;
 }

 inline int get(int x)
 {
     return x == son[f[x]][];
 }

 inline void update(int now)
 {
     if(now)
     {
         size[now] = ;
         if(ls) size[now] += size[ls];
         if(rs) size[now] += size[rs];

         max[now] = key[now];
         if(ls) max[now] = Max(max[now], max[ls]);
         if(rs) max[now] = Max(max[now], max[rs]);
     }
 }

 inline void pushdown(int now)
 {
     if(rev[now])
     {
         swap(ls, rs);
         if(ls) rev[ls] ^= ;
         if(rs) rev[rs] ^= ;
         rev[now] = ;
     }
     if(add[now])
     {
         if(ls) add[ls] += add[now], key[ls] += add[now], max[ls] += add[now];
         if(rs) add[rs] += add[now], key[rs] += add[now], max[rs] += add[now];
         add[now] = ;
     }
 }

 inline void build(int x, int y, int fa, int &now)
 {
     if(x > y) return;
     int mid = (x + y) >> ;
     now = ++cnt;
     f[now] = fa;
     build(x, mid - , now, ls);
     build(mid + , y, now, rs);
     update(now);
 }

 inline void rotate(int x)
 {
     pushdown(f[x]);
     pushdown(x);
     int old = f[x], oldf = f[old], wh = get(x);

     son[old][wh] = son[x][wh ^ ];
     f[son[old][wh]] = old;

     if(oldf) son[oldf][old == son[oldf][]] = x;
     f[x] = oldf;

     son[x][wh ^ ] = old;
     f[old] = x;

     update(old);
     update(x);
 }

 inline void splay(int x, int to)
 {
     for(int fa; (fa = f[x]) != to; rotate(x))
         if(f[fa] != to)
             rotate(get(x) ^ get(fa) ? x : fa);
     if(!to) root = x;
 }

 inline int find(int x)
 {
     int now = root;
     while()
     {
         pushdown(now);
         if(x <= size[ls]) now = ls;
         else
         {
             x -= size[ls];
             if(x == ) return now;
             x--;
             now = rs;
         }
     }
 }

 int main()
 {
     int i, k, x, y, v;
     scanf("%d %d", &n, &m);
     a[] = -INF, a[n + ] = -INF;
     build(, n + , , root);
     for(i = ; i <= m; i++)
     {
         scanf("%d %d %d", &k, &x, &y);
         x = find(x);
         y = find(y + );
         splay(x, );
         splay(y, x);
         if(k == )
         {
             scanf("%d", &v);
             add[son[son[root][]][]] += v;
             max[son[son[root][]][]] += v;
             key[son[son[root][]][]] += v;
             update(son[root][]);
             update(root);
         }
         else if(k == ) rev[son[son[root][]][]] ^= ;
         else printf("%d\n", max[son[son[root][]][]]);
     }
     return ;
 }