algorithm的冷门函数

#include<bits/stdc++.h>
using namespace std;

int main()
{
    int n;
    cin >> n;
    vector<int> a(n);
    for (int i=0;i<n;i++)
        cin >> a[i];
    sort(a.begin(),a.end());
    for (int i=0;i<n;i++)
    {
        if (a[i]!=a[i-1])
            cout << a[i] << ' ' << count(a.begin(),a.end(),a[i]) << endl;
    }
    return 0;
}