字典树整理加几个例题

首先粘贴一个入门博客

https://www.cnblogs.com/TheRoadToTheGold/p/6290732.html

接下来沾上我的板子

//找前缀
#include
#include
#include
using namespace std;
const int maxn = 2000010;

int n, m, rt, trie[maxn][27], tot, sum[maxn];
string str;

void insertit(int rt)
{
    int len = str.size();
    for(int i = 0; i < len; i++)
    {
        int x = str[i] - 'a';
        if(trie[rt][x] == 0) trie[rt][x] = ++tot;
        sum[trie[rt][x]]++;
        rt = trie[rt][x];
    }
}
int tofind(int rt)
{
    int len = str.size();
    for(int i = 0; i < len; i++)
    {
        int x = str[i] - 'a';
        if(trie[rt][x] == 0) return 0;
        rt = trie[rt][x];
    }
    return sum[rt];
}

入门题讲解：

（1）查询前缀是否存在

#include
#include
using namespace std;
const int maxn = 2000010;

int n, m, rt, trie[maxn][27], tot;
string str;

void insertit(int rt)
{
    int len = str.size();
    for(int i = 0; i < len; i++)
    {
        int x = str[i] - 'a';
        if(trie[rt][x] == 0) trie[rt][x] = ++tot;
        rt = trie[rt][x];
    }
}
bool tofind(int rt)
{
    int len = str.size();
    for(int i = 0; i < len; i++)
    {
        int x = str[i] - 'a';
        if(trie[rt][x] == 0) return false;
        rt = trie[rt][x];
    }
    return true;
}
int main()
{
    cin >> n;
    rt = 1; tot = 1;
    while(n--)
    {
        cin >> str;
        insertit(rt);
    }
    cin >> m;
    while(m--)
    {
        cin >> str;
        if(tofind(rt)) puts("YES");
        else puts("NO");
    }
    return 0;
}