I stuck at a problem ,It was a basically implementation problem ,It passed all the test cases But I have doubt regarding its time complexity.

for (int i = 0; i < 1e6 + 100; i++) {
    sort(v[i].begin(), v[i].end());
}

The time complexity of this loop seems to be O(nnlogn) .Then It should definitely fail because n value can be 10^6.Even O(n*n) fail for such higher value of n,I have seen already so many times on codeforces.

What is its correct time complexity??

Problem link

Please forgive me if it is too basic!

#include <iostream>
#include <cmath>
#include <algorithm>
#include <vector>
#include <cstring>
using namespace std;
const int N = 1e6 + 100;
vector<int> a, f(1e6 + 100);
vector<int>v[N];
int main() {
    int n;
    cin >> n;
    a.resize(n);
    int mx = -1;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
        f[a[i]]++;
        v[a[i]].push_back(i);
        mx = max(mx, f[a[i]]);
    }
    for (int i = 0; i < 1e6 + 100; i++) {
        sort(v[i].begin(), v[i].end());
    }
    int diff = INT_MAX;
    int ans[2];
    for (int i = 0; i < 1e6 + 100; i++) {
        if (f[i] == mx) {
            int temp = v[i][v[i].size() - 1] - v[i][0];
            if (diff > temp) {
                diff = temp;
                ans[0] = v[i][0];
                ans[1] = v[i][v[i].size() - 1];
            }
        }
    }
    cout << ans[0] + 1 << " " << ans[1] + 1;

}