统计难题HDUOJ-1251（字典树统计前缀次数）

思路：字典树模板题

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <set>
#include <sstream>
#include<string>
#include<queue>
#include<stack>
#include<map>
#include<cmath>
#include<cctype>
#include<cstring>
#include<cstdlib>
#define MAXX 100005
#define SIS std::ios::sync_with_stdio(false)
#define ll long long
#define INF 0x3f3f3f3f
//#include<bits/stdc++.h>
using namespace std;
//const int MAX =100;
const double PI = 3.14159265359;
//const int mod = 1e9 + 7;
int n, m;
struct node
{
    int x, y;ll num;
    bool operator <(const node other)const
    {
        return num > other.num;

    }
};
int trie[400001][26], len, root, tot,sum[400001];
bool p;
char s[12];
void insert()
{
    len = strlen(s);
    root = 0;
    for (int i = 0; i < len; i++)
    {
        int id = s[i] - 'a';
        if (!trie[root][id]) trie[root][id] = ++tot;
        sum[trie[root][id]]++;
        root = trie[root][id];
    }
}
int search()
{
    root = 0;
    len = strlen(s);
    for (int i = 0; i < len; i++)
    {
        int id = s[i] - 'a';
        if (!trie[root][id])return 0;
        root = trie[root][id];
    }
    return sum[root];
}
int main()
{
    while (gets(s)&&s[0]!='\0')
            insert();
    while (~scanf("%s", s))
    {
        //cout<<s<<endl;
        int ans = search();
        cout << ans << endl;
    }
    return 0;

}