我为什会超时啊 P5266 【深基17.例6】学籍管理

#include<iostream>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<vector>
using namespace std;
const int N=100010;
struct student {
    string name;
    int score;
};
int sum;
student a[N];
int main() {
    int n;
    cin>>n;
    for(int i=0;i<n;i++) {
        int x;
        cin>>x;
        if(x==1) {
            cin>>a[i].name;
            sum++;
            cin>>a[i].score;
            cout<<"OK"<<endl;
        }
        if(x==2) {
             string c;
            cin>>c;
            for(int j=0;j<n;j++) {
                if(a[j].name==c) {cout<<a[j].score<<endl;break;}
                if(a[j].name!=c&&n-1==j)cout<<"Not found"<<endl;
            }
        }
        if(x==3) {
            string c;
            cin>>c;
            for(int j=0;j<n;j++) {
                if(a[j].name==c) {
                    cout<<"Deleted successfully"<<endl;
                    a[j].name="!!!";
                    sum--;
                }
                if(j==n-1&&a[i].name==c) {
                    cout<<"Not found"<<endl;
            }
        }
    }
        if(x==4) cout<<sum<<endl;
    }
	return 0;
}