Shared code

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

int32_t main()
{
    ios_base::sync_with_stdio(false); cin.tie(0); //necessary to pass time limits
    int x, n;
    cin >> x >> n;
    set<pair<int,int>> S;
    multiset<int> dist;
    dist.insert(x);
    S.insert({0,x});
    for(int i = 0; i < n; i++)
    {
        int y; cin >> y;
        auto it = S.lower_bound({y, y}); it--;  // nearest range with left point < y
        auto Q = *it;
        int A = Q.first, B = Q.second;
        S.erase({A,B});                         // remove the big range
        S.insert({A,y}), S.insert({y,B});       // create two smaller ranges A - y and y - B
        dist.erase(dist.find(B-A));             // remove old dist
        dist.insert(y-A), dist.insert(B-y);     // insert new ones
        auto it3 = dist.end(); it3--;           // largest value in the dist set
        cout << *it3 << " ";
    }
}