Help me in solving XSQR problem

help
,
1

My issue

Whats the difference in my code and others code, why am i getting tle

My code

#include<bits/stdc++.h>

using namespace std;
#define int long long

vector < int > a;
signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int t;
    cin >> t;
    while (t--) {
        int n;
        cin >> n;
        a.resize(n);
        for (int i = 0; i < n; i++) {
            cin >> a[i];
        }
        unordered_map < int, int > mp;
        for (int i = 0; i < n; i++) {
            for (int j = i + 1; j < n; j++) {
                mp[a[i] ^ a[j]]++;
            }
        }
        int ans = 0;
        for (auto & v: mp) {
            int k = v.second;
            ans += (k * (k - 1));
        }
        cout << 4 LL * ans << "\n";
    }
    return 0;
}

Problem Link: Xometry (Easy Version) Practice Coding Problem

2

change map with vector as map can sometimes in worst case takes more time
vectormp(2000000,0)
your code now will get accepted