Submission #971016

#	Time	Username	Problem	Language	Result	Execution time	Memory
971016		_rain_	Split the sequence (APIO14_sequence)	C++14	50 / 100	2073 ms	48972 KiB

sequence

/** author : _RAIN_ **/
#include<bits/stdc++.h>
using namespace std;

using i64 = long long;
using ui64 = unsigned long long;

#define MASK(x) ((i64)(1) << (x))
#define BIT(mask , x) (((mask) >> (x)) & (1))

template<class T>
    bool maximize(T &a , T b) {if (a < b) return a = b , true; else return false;}
template<class T>
    bool minimize(T &a , T b) {if (a > b) return a = b , true; else return false;}
template<class T>
    T gcd(T x , T y) {while (y) swap(y , x %= y); return x;}
template<class T>
    T lcm(T x , T y) {return (x * y) / gcd(x , y);}
#define sz(x) (int)((x).size())
struct Line
{
    i64 a , b;
    Line(i64 a , i64 b) : a(a) , b(b) {};
};
struct Hull
{
    Line X;
    double intersec;
};
class Convex_hull
{
    public:
        vector<Hull> line;
        double getintersec(Line x , Line y)
        {
            return (double)(y.b - x.b) / (x.a - y.a);
        }
        i64 getval(Line a , i64 x)
        {
            return a.a * x + a.b;
        }
        void addline(Line a)
        {
            int n = sz(line);
            while (n > 1 && getintersec(line[n - 2].X , a) <= getintersec(line[n - 1].X , line[n - 2].X))
                line.pop_back() , --n;
            if (!sz(line))
                line.push_back({a , LLONG_MIN}); else line.push_back({a , getintersec(a , line[n - 1].X)});
            return;
        }
        i64 find(i64 val)
        {
            int low = 0 , high = sz(line) - 1 , p = 0;
            while (low <= high)
            {
                int mid = low + high >> 1;
                if (line[mid].intersec <= val) p = mid , low = mid + 1;
                    else high = mid - 1;
            }
            return getval(line[p].X , val);
        }
        void add(i64 a , i64 b)
        {
            addline(Line{a , b});
            return;
        }
};

const int maxn = 1e4;
const int maxk = 200;
i64 dp[maxn + 2][maxk + 2] , g[maxn + 2] , a[maxn + 2] , pre[maxn + 2];
int trace[maxn + 2][maxk + 2];
int n , k;

void solve()
{
    for (int used = 1; used <= k; ++used)
    {
        for (int i = 1; i <= n; ++i)
        {
            for (int j = 1; j < i; ++j)
                if (maximize(dp[i][used] , dp[j][used - 1] + (pre[n] - pre[i - 1]) * (pre[i - 1] - pre[j - 1])))
                    trace[i][used] = j;
        }
    }
}

int32_t main(void)
{
    cin.tie(nullptr)->sync_with_stdio(false);
    const string name = "main";
    if (fopen((name + ".inp").c_str() , "r"))
    {
        (void)!freopen((name + ".inp").c_str() , "r" , stdin);
        (void)!freopen((name + ".out").c_str() , "w+", stdout);
    }
    cin >> n >> k;
    memset(pre , 0 , sizeof pre);
    for (int i = 1; i <= n; ++i) cin >> a[i];
    for (int i = 1; i <= n; ++i) pre[i] = pre[i - 1] + a[i];
    memset(dp , -0x3f , sizeof dp);
    dp[1][0] = 0;
    solve();
    i64 answer = LLONG_MIN;
    int v = 1 , ks = 1;
    for (int i = 1; i <= n; ++i) 
        if (maximize(answer , dp[i][k]))
            v = i - 1 , ks = i;
    cout << dp[ks][k] << '\n';
    vector<int> recall;
    while (k)
    {
        recall.emplace_back(v);
        v = trace[ks][k] - 1;
        ks = trace[ks][k];
        --k;
    }
    reverse(recall.begin() , recall.end());
    for (auto& v : recall) cout << v << ' ';
}

Compilation message (stderr)

sequence.cpp: In member function 'i64 Convex_hull::find(i64)':
sequence.cpp:56:31: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   56 |                 int mid = low + high >> 1;
      |                           ~~~~^~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 11 / 11
• Subtask 3: 11 / 11
• Subtask 4: 17 / 17
• Subtask 5: 0 / 21
• Subtask 6: 0 / 29