通过迭代器来获得对应元素的下标╮(╯▽╰)╭ ~

#include <iostream>
#include <cstdio>
#include <vector>
#include <map>
#include <set>
#include <string>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <utility>
#include <algorithm>

using namespace std;

map<int, int> m;
map<int, int> :: iterator it, firs, e;
vector <int> v;

int a[15];

int main()
{

for (int i=0; i<=10; i++)
{
a[i] = i;
v.push_back (i);
m[i]++;
}
for (it=m.begin(); it!=m.end(); it++)
{
cout << it->first << " " << it->second << endl;
}
firs = m.begin();
e = m.end();
cout << distance(firs, e) << " ~~ " << a[distance(firs, e)-1] << " ~~ " << a[(int)m.size()-1]<< endl;
//高能预警：如果下面一行第二个输出是a[distance(v.begin(), v.end())-1]就对啦
cout << distance(v.begin(), v.end())  << " ~~ " << a[distance(v.begin(), v.end())] << endl;
return 0;
}