15. Traffic Lights.cpp

#include "iostream"
#include "bits/stdc++.h"

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef vector<ll> vl;
typedef vector<string> vs;
typedef set<ll> sl;
typedef map<string, ll> msl;
typedef map<ll, ll> mll;
typedef unordered_map<ll, ll> umll;
typedef pair<string, ll> psl;
typedef pair<ll, ll> pll;

#define fastio() ios_base::sync_with_stdio(0);cin.tie(NULL)
#define PB push_back
#define MP make_pair
#define F first 
#define S second
#define I iterator
#define REP(i,a,b) for (ll i = a; i < b; i++)
#define REPR(i,a,b) for (ll i = a; i > b; i--)
#define REPJ(i,a,b,j) for (ll i = a; i < b; i+=j)
#define REPIT(it,o) for (auto it = o.begin(); it != o.end(); it++)
#define REPITR(it,o) for (auto it = o.rbegin(); it != o.rend(); it++)
#define ALL(a) a.begin(),a.end()
#define ALLR(a) a.rbegin(),a.rend()

int main() {
    fastio();
    ll x,n; cin >> x >> n;
    pll last = MP(0,x);
    REP(i,0,n){
        ll t; cin >> t;
        if (t > last.F && t < last.S){
            if (t-last.F > last.S-t){
                last = MP(last.F,t);
            } else {
                last= MP(t,last.S);
            }
        }
        cout << last.S-last.F << " ";
    }
}

// TODO
// - initial approach
// maintain a var for the largest gap, check if the new light falls in this gap, update if does
// wa