按需求挑一个

运行下面这段程序：

#include <algorithm>
#include <iostream>
#include <map>
#include <string>
#include <vector>
using namespace std;

string choose(const string& need) {
    map<string, string> pick = {
        {"区间和还会改", "树状数组"},
        {"海量去重可误判", "布隆过滤器"},
        {"磁盘上少读盘", "B+树"},
        {"有序且增删频繁", "平衡树"},
    };
    auto it = pick.find(need);
    if (it == pick.end()) return "还得再想想";
    return it->second;
}

int main() {
    cout << choose("海量去重可误判") << endl;
}

（本题用 g++ -std=c++17 -O0 编译。）