[Trie树][YbtOJ]A. 【例题1】前缀统计

解析

Trie树基础题, 将 \(s\) 串全部加到Trie树里面, 然后记录以某个节点为终点的单词的个数 val[], 然后将询问串 \(T\) 搜索一遍, 遍历过完的点就讲 \(val[hhd]\) 给加上.

Code

#include <bits/stdc++.h>
#define N 100005
using namespace std;

char se[N];
int n, m;
struct Trie
{
	int tag, val[N], st[N][30];
	Trie ()
	{
		tag = 1;
		memset (val, 0, sizeof (val));
		memset (st[0], 0, sizeof (st[0])); 
	}
	void insert (char *s)
	{
		int hhd = 1, len = strlen (s + 1);
		for (int i = 1; i <= len; ++ i)
		{
			int c = s[i] - 'a';
			if (!st[hhd][c])
				st[hhd][c] = ++ tag;
			hhd = st[hhd][c];
		}
		val[hhd] ++;
	}
	int search (char *s)
	{
		int hhd = 1, len = strlen(s + 1), add = 0;
		for (int i = 1; i <= len; ++ i)
		{
			int c = s[i] - 'a';
			if (!st[hhd][c])
			{
				return add;
			}
			hhd = st[hhd][c];
			add += val[hhd];
		}
		return add;
	}
}tree;

int main ()
{
	scanf ("%d%d", &n, &m);
	for (int i = 1; i <= n; ++ i)
	{
		scanf ("%s", se + 1);
		tree.insert (se); 
	}
	for (int i = 1; i <= m; ++ i)
	{
		scanf ("%s", se + 1);
		int ans = tree.search (se);
		printf ("%d\n", ans); 
	}
	return 0;
}