Submission #918669

#	Time	Username	Problem	Language	Result	Execution time	Memory
918669		Boycl07	Split the sequence (APIO14_sequence)	C++17	100 / 100	592 ms	84056 KiB

sequence

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

#define rep(i, n) for(int i = 1; i <= n; ++i)
#define forn(i, l, r) for(int i = l; i <= r; ++i)
#define ford(i, r, l) for(int i = r; i >= l; --i)
#define FOR(i, n) for(int i = 0; i < n; ++i)
#define fi first
#define se second
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pb push_back
#define endl "\n"
#define task "split"
#define sz(a) int(a.size())
#define C(x, y) make_pair(x, y)
#define all(a) (a).begin(), (a).end()
#define bit(i, mask) (mask >> i & 1)

template<typename T> bool maximize(T &res, const T &val) { if (res < val){ res = val; return true; }; return false; }
template<typename T> bool minimize(T &res, const T &val) { if (res > val){ res = val; return true; }; return false; }

inline int readInt()       {char c;while(c=getchar(),c!='-'&&(c<'0'||c>'9'));bool sign=(c=='-');if(sign)c=getchar();int n=c-'0';while(c=getchar(),c>='0'&&c<='9')n=10*n+c-'0';return(!sign)?n:-n;}
inline ll readLong()       {char c;while(c=getchar(),c!='-'&&(c<'0'||c>'9'));bool sign=(c=='-');if(sign)c=getchar();ll  n=c-'0';while(c=getchar(),c>='0'&&c<='9')n=10*n+c-'0';return(!sign)?n:-n;}
inline string readString() {char c;while(c=getchar(),c==' '||c=='\n'||c=='\t');string s({c});while(c=getchar(),c!=EOF&&c!=' '&&c!='\n'&&c!='\t')s+=c;return s;}


const int N = 1e5 + 4;
const int M = 3e5 + 3;
const int INF = 1e9 + 3;
const ll LINF = 1e18;
const int A = 26 + 2;
const int K = 200 + 3;

int n, k;

int a[N];

int sum[N];

ll dp[N][2];

int opt[N][K];

int j = 0;

int f = 0;

double slope(pll x, pll y)
{
    return double (1) * (y.se - x.se) / (x.fi - y.fi);
}

ll get(pll line, ll x) {return line.fi * x + line.se;}

pll line[N];
deque<int> cht;
bool bad(pll x, pll y, pll z)
{
    if(z.fi == y.fi) return z.se >= y.se;
    return slope(x, y) >= slope(y, z);
}

void solve()
{
    cin >> n >> k;
    rep(i, n) cin >> a[i], sum[i] = sum[i - 1] + a[i];
    dp[0][0] = 0;
    rep(i, n) dp[i][0] = -LINF;

    rep(_, k + 1)
    {
        f ^= 1;
        ++j;
        forn(i, 0, n) dp[i][f] = -LINF;
        while(sz(cht)) cht.pop_back();
        rep(i, n)
            line[i] = {sum[i - 1], dp[i - 1][f ^ 1] - 1ll * sum[i - 1] * sum[i - 1]};

        rep(i, n )
        {
            while(sz(cht) >= 2 && bad(line[cht[sz(cht) - 2]], line[cht.back()], line[i]))
                cht.pop_back();
            cht.push_back(i);
            while(sz(cht) >= 2 && get(line[cht[0]], sum[i]) <= get(line[cht[1]], sum[i]))
                cht.pop_front();
            maximize(dp[i][f], get(line[cht[0]], sum[i]));
            opt[i][j] = cht[0];
        }
    }
    cout << dp[n][f] << endl;
    int x = n;
    ford(i, k, 1)
    {
        x = opt[x][i + 1] - 1;
        cout << x << " ";
    }
}

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

    int TC = 1;

    if(fopen(task".inp", "r"))
    {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }


    while(TC--)
    {
        solve();
        cout << endl;
    }

    return 0;
}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:112:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  112 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
sequence.cpp:113:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  113 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 11 / 11
• Subtask 3: 11 / 11
• Subtask 4: 17 / 17
• Subtask 5: 21 / 21
• Subtask 6: 29 / 29