#include <stdio.h>
#include <map>
#include <set>
#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;
int main()
{
    vector<int> v;
    v.resize(10);
    for (int i = 0; i < 10; ++i)
        v[i] = 2*i;
    std::vector<int>::iterator low,up;
    low = std::lower_bound(v.begin(), v.end(), 6);
    up = std::upper_bound(v.begin(), v.end(), 6);

    std::cout<<"low:"<<*low<<endl;
    std::cout<<"up:"<<*up<<endl;
    return 0;
}

// 输出：
6
8

lower_bound()