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[2];
    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[0] = c -> son[1] = NULL;
        c -> sz = 0, c -> tail = 0;
        return c++;
    }
    #undef Len
     
    void insert(int x) {
        ++this -> sz;
        if (x == 0) {
            ++this -> tail;
            return;
        }
        int t = read();
        if (!this -> son[t]) this -> son[t] = new()trie;
        this -> son[t] -> insert(x - 1);
    }
     
    int query(int x) {
        if (x == 0) return this -> sz;
        int t = read();
        if (!this -> son[t]) {
            while (--x) read();
            return this -> tail;
        }
        return this -> son[t] -> query(x - 1) + this -> tail;
    }
} *t;
 
int n, m;
 
int main() {
    int i;
    n = read(), m = read();
    t = new()trie;
    for (i = 1; i <= n; ++i) t -> insert(read());
    for (i = 1; i <= m; ++i) printf("%d
", t -> query(read()));
    return 0;
}
 
inline int read() {
    static int x;
    static char ch;
    x = 0, ch = getchar();
    while (ch < '0' || '9' < ch)
        ch = getchar();
    while ('0' <= ch && ch <= '9') {
        x = x * 10 + ch - '0';
        ch = getchar();
    }
    return x;
}