Concentric Tubes

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

signed main() {
    int n;
    cin >> n;
    vector<tuple<int, int, int, int>> arr(0);

    vector<tuple<int, int, int>> disks(n);
    for (int i = 0; i < n; i++)
        cin >> get<0>(disks[i]);
    for (int i = 0; i < n; i++)
        cin >> get<1>(disks[i]);
    for (int i = 0; i < n; i++)
        get<2>(disks[i]) = i;
    sort(disks.begin(), disks.end(), [](const tuple<int, int, int>& a, const tuple<int, int, int>& b){ return (int)get<1>(a) < (int)get<1>(b); });
    arr.push_back({get<1>(disks[0]), 1, -1, get<2>(disks[0])});

    for (int i = 1; i < n; i++)
    {
        auto it = std::upper_bound(arr.begin(), arr.end(), tuple<int, int, int, int>{get<0>(disks[i]), INT_MAX, 0, 0});
        int inside = 0;
        if (it != arr.begin())
        {
            it--;
            inside = get<1>(*it);
        }
        else
            it--;
        inside++;
        if (inside > get<1>(arr.back()))
            arr.push_back(tuple<int, int, int, int>{get<1>(disks[i]), inside, it - arr.begin(), get<2>(disks[i])});
    }
    cout << get<1>(arr.back()) << "\n";

    vector<int> result;
    int arrIdx = arr.size()-1;
    while (arrIdx != -1)
    {
        result.push_back(get<3>(arr[arrIdx]) + 1);
        arrIdx = get<2>(arr[arrIdx]);
    }
    reverse(result.begin(), result.end());
    for (auto x : result)
        cout << x << " ";
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED