题目连接

https://www.acwing.com/problem/content/submission/837/

思路

我们通过trie树的结构将我们要插入的字符串插进去，但是要注意一点，最后我们要统计一下插入的字符串的个数，然后查找的时候同理，这个结构相当于每一层有26个字符

代码

#include<bits/stdc++.h>
using namespace std;
//----------------自定义部分----------------
#define ll long long
#define mod 1000000009
#define endl "\n"
#define PII pair<int,int>

int dx[4]={0,-1,0,1},dy[4]={-1,0,1,0};

ll ksm(ll a,ll b) {
	ll ans = 1;
	for(;b;b>>=1LL) {
		if(b & 1) ans = ans * a % mod;
		a = a * a % mod;
	}
	return ans;
}

ll lowbit(ll x){return -x & x;}

const int N = 2e6+10;
//----------------自定义部分----------------
int n;

int nextt[N][26],cnt,vis[N];
void insert(string S){
	int l = S.size(),p = 0;
	for(int i = 0;i < l; ++i) {
		int c = S[i] - 'a';
		if(!nextt[p][c]) nextt[p][c] = ++ cnt;
		p = nextt[p][c];
	}
	vis[p]++;
}

int find(string S){
	int l = S.size(),p = 0;
	for(int i = 0;i < l; ++i){
		int c = S[i] - 'a';
		if(!nextt[p][c]) return 0;
		p = nextt[p][c];
	}
	return vis[p];
}

int main()
{
	cin>>n;
	char op;
	string s;
	while(n--){
		cin>>op>>s;
		if(op == 'I') insert(s);
		else cout<<find(s)<<endl;
	}
	
	return 0;
}