BZOJ1590 [Usaco2008 Dec]Secret Message 秘密信息

建立一颗trie树，记录下来每个点以它为结尾的字符串的个数cnt，和它的子树内有多少字符串size

于是查询的时候就只需要把沿途的cnt加起来，再加上最后的size就好了

 /**************************************************************
     Problem: 1590
     User: rausen
     Language: C++
     Result: Accepted
     Time:320 ms
     Memory:3892 kb
 ****************************************************************/

 #include <cstdio>

 using namespace std;

 inline int read();

 struct trie {
     trie *son[];
     int sz, tail;

     #define Len (1 << 16)
     void* operator new(size_t) {
         static trie *mempool, *c;
         if (c == mempool)
             mempool = (c = new trie[Len]) + Len;
         c -> son[] = c -> son[] = NULL;
         c -> sz = , c -> tail = ;
         return c++;
     }
     #undef Len

     void insert(int x) {
         ++this -> sz;
         if (x == ) {
             ++this -> tail;
             return;
         }
         int t = read();
         if (!this -> son[t]) this -> son[t] = new()trie;
         this -> son[t] -> insert(x - );
     }

     int query(int x) {
         if (x == ) return this -> sz;
         int t = read();
         if (!this -> son[t]) {
             while (--x) read();
             return this -> tail;
         }
         return this -> son[t] -> query(x - ) + this -> tail;
     }
 } *t;

 int n, m;

 int main() {
     int i;
     n = read(), m = read();
     t = new()trie;
     for (i = ; i <= n; ++i) t -> insert(read());
     for (i = ; i <= m; ++i) printf("%d\n", t -> query(read()));
     return ;
 }

 inline int read() {
     static int x;
     static char ch;
     x = , ch = getchar();
     while (ch < '' || '' < ch)
         ch = getchar();
     while ('' <= ch && ch <= '') {
         x = x *  + ch - '';
         ch = getchar();
     }
     return x;
 }