Code: Lost Civilization (Hard Version)

#include <bits/stdc++.h>

using i64 = long long;
using u64 = unsigned long long;
using u32 = unsigned;

using u128 = unsigned __int128;
using i128 = __int128;

void solve() {
    int n;
    std::cin >> n;

    std::vector<int> a(n);
    for (int i = 0; i < n; i++) {
        std::cin >> a[i];
    }

    std::vector<std::pair<int, int>> stk;
    i64 ans = 0;
    i64 res = 0;
    for (int i = n - 1; i >= 0; i--) {
        while (!stk.empty() && stk.back().first == a[i] + 1) {
            res -= stk.back().second;
            stk.pop_back();
        }
        stk.emplace_back(a[i], n - i);
        res += n - i;
        ans += res;
    }

    std::cout << ans << "\n";
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    int t;
    std::cin >> t;

    while (t--) {
        solve();
    }

    return 0;
}