Language: C++

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

typedef unsigned long long ull;
typedef long long ll;
typedef  double ld;



#define int ll


typedef pair<int, int> pii;
typedef pair<pii, pii> piii;
typedef vector<piii> vpii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector< vi > vvi;
typedef vector< vvi > vvvi;
typedef vector<pii> vpi;
typedef vector<short> vs;
typedef vector<vs> vvs;
typedef vector<vvs> vvvs;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;
typedef vector<ld> vld;
typedef vector<vld> vvld;
typedef vector<vvld> vvvld;
typedef vector<string> vst;
typedef vector<vst> vvst;
typedef pair<ld, ld> pld;
typedef vector<pld> vpd;
typedef complex<double> base;


#define inmin(a, b) a = min(a, (b))
#define inmax(a, b) a = max(a, (b))
#define mp(a, b) make_pair(a, (b))
#define ALL(a) a.begin(),a.end()
#define RALL(a) a.rbegin(),a.rend()
#define sqr(x) ((x) * (x))
#define fori(i, n) for(int i = 0; i < int(n); ++i)
#define SZ(a) ((int)((a).size()))
#define triple(T) tuple<T, T, T>
#define quad(T) tuple<T, T, T, T>
#define watch(x) cout << (#x) << " = " << x << endl;
#ifdef MAX_HOME
#define cerr cout
#else
#define cerr if (false) cerr
#endif


const double PI = 2 * acos(0.0);

const string DIGITS = "0123456789";
const string ALPH = "abcdefghijklmnopqrstuvwxyz";

istream &operator >> (istream &in, pii &a)
{
    in >> a.first >> a.second;
    return in;
}


ostream &operator << (ostream &out, pii &a)
{
    out << a.first << ' ' << a.second;
    return out;
}


istream &operator >> (istream &in, pld &a)
{
    in >> a.first >> a.second;
    return in;
}


ostream &operator << (ostream &out, pld &a)
{
    out << a.first << ' ' << a.second;
    return out;
}


template <class T0, class T1>
inline ostream & operator << (ostream &out, pair<T0, T1> &a) {
    return out << "{" << a.first << ", " << a.second << "}";
}

template <class T0, class T1, class T2>
inline ostream & operator << (ostream &out, tuple<T0, T1, T2> &a) {
    return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a) << "}";
}

template <class T0, class T1, class T2, class T3>
inline ostream & operator << (ostream &out, tuple<T0, T1, T2, T3> &a) {
    return out << "{" << get<0>(a) << ", " << get<1>(a) <<
               ", " << get<2>(a) << ", " <<  get<3>(a) << "}";
}

template<class T>
inline ostream & operator << (ostream &out, vector<T> &a) {
    out << "[";
    fori (i, a.size())
        out << a[i] << vector<string>{", ", "]  "}[i + 1 == a.size()];
    return out;
}


void smain();

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

#ifdef ART_HOME
    freopen("input.txt", "r", stdin);
    clock_t start = clock();
#endif
    cout << setprecision(20) << fixed;
    smain();
#ifdef ART_HOME
    cout << "\n\n\n\nTOTAL EXECUTION TIME: " << float( clock () - start ) /  CLOCKS_PER_SEC << endl;
#endif
}

const int oo = 1e18;
const int N = 1 << 18, K = 100, alpha = 256, LOG = 20, M = 1e4 + 10, B = 100;
const ld pi = 2 * atan2(1, 0), EPS = 1e-9;


pii t[N << 1];


int func(int x, pii cur)
{
    return cur.first * x + cur.second;
}


int get(int x, int l = 1, int r = N, int ind = 1)
{
    int v = func(x, t[ind]);

    if (l == r)
        return v;

    int m = (l + r) >> 1;

    if (x <= m)
        return min(v, get(x, l, m, ind << 1));
    else
        return min(v, get(x, m + 1, r, ind << 1 | 1));
}


void add(pii nw, int l = 1, int r = N, int ind = 1)
{
    int m = (l + r) >> 1;
    pii old = t[ind];

    bool lef = func(l, nw) < func(l, old);
    bool mid = func(m, nw) < func(m, old);

    if (mid)
        swap(t[ind], nw);

    if (l == r)
        return;

    if (mid != lef)
        add(nw, l, m, ind << 1);
    else
        add(nw, m + 1, r, ind << 1 | 1);
}


int stupid(vi lel, int c)
{
    int n = SZ(lel);
    vi dp(n);


    for (int i = 1; i < n; ++i) {
        dp[i] = oo;

        for (int j = 0; j < i; ++j)
            dp[i] = min(dp[i], dp[j] + sqr(lel[i] - lel[j]) + c);
    }

    return dp.back();
}


int clever(vi lel, int C)
{
    int n = SZ(lel);

    add(mp(-2 * lel[0], sqr(lel[0])));

    for (int i = 1; i < n; ++i)
    {
        int v = get(lel[i]) + sqr(lel[i]) + C;

        if (i + 1 == n)
            return v;

        add(mp(-2 * lel[i], v + sqr(lel[i])));
    }
}


void print(vi lel, int C)
{
    ofstream cout("output.txt");
    cout << SZ(lel) << ' ' << C << '\n';
    for (int v : lel)
        cout << v << ' ';
}


void smain()
{
    srand(time(0));

//    int T = 0;
//    while(1) {
//        cout << T << endl;
//        T++;

        for (int i = 0; i < (N << 1); ++i)
            t[i] = mp(0, oo);

        int n = 1000, C = rand();
        cin >> n >> C;

        vi lel(n);
        for (int i = 0; i < n; ++i)
//            lel[i] = rand();

//        stable_sort(ALL(lel));
            cin >> lel[i];




        if (stupid(lel, C) != clever(lel, C)) {
            assert(0);
            print(lel, C);
            cout << stupid(lel, C) << endl << clever(lel, C) << endl;
            exit(0);

        }
//                    int a = 1;
//            assert(0);
        cout << clever(lel, C);
    }
}

Compiler output:
a.cc:261:1: error: expected declaration before '}' token
  261 | }
      | ^
a.cc: In function 'll clever(vi, ll)':
a.cc:213:1: warning: control reaches end of non-void function [-Wreturn-type]
  213 | }
      | ^