文章目录

• • 1. 题目来源
  • 2. 题目解析

1. 题目来源

链接：P5266 【深基17.例6】学籍管理

2. 题目解析

水题，unordered_map<> 基本使用。

代码：

// https://www.luogu.com.cn/problem/P5266

#include <iostream>
#include <cstdio>
#include <string>
#include <unordered_map>

using namespace std;

int n;
unordered_map<string, int> h;

int main() {
    scanf("%d", &n);
    for (int i = 0; i < n; i ++ ) {
        int op;
        string s;
        int sum;
        scanf("%d", &op);
        if (op == 1) {
            cin >> s >> sum;
            h[s] = sum, printf("OK\n");
        }
        else if (op == 2) {
            cin >> s;
            if (h.count(s)) printf("%d\n", h[s]);
            else printf("Not found\n");
        }
        else if (op == 3) {
            cin >> s;
            if (h.count(s)) h.erase(s), printf("Deleted successfully\n");
            else printf("Not found\n");
        }
        else printf("%d\n", h.size());
    }
}