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;
}