• I was solving this problem from the last 2 hour almost -> 1334C - Circle of Monsters
• I made quite submissions but I was getting TLE for my code.
• Then I looked for some red coders solution and the thing is the logic and implementation was same, but I still submit the red coder's code and I'm surprised that IT STILL GOT TLE WHY ?

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

#define ll long long
#define ff first
#define ss second

void solve() {
    ll n; cin >> n;
    vector<ll> a(n), b(n);
    for (ll i = 0; i < n; i++)
        cin >> a[i] >> b[i];
    vector<ll> cost(n, 0);
    for (ll i = 0; i < n; i++)
        cost[i] = max(0LL, a[i] - b[(i + n - 1) % n]);

    ll sum = accumulate(cost.begin(), cost.end(), 0LL);
    ll ans = (ll)1e18;
    for (ll i = 0; i < n; i++) {
        ans = min(ans, sum - cost[i] + a[i]);
    }
    cout << ans << endl;
}

int main() {
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    ll tc;
    cin >> tc;
    while (tc--)
        solve();
    return 0;
}

• I don't know what's the problem in this very simple and clean code and still I'm facing this issue.
• Can anyone please consider this problem and tell me, why it is giving me TLE ?