Submission #928768

#	Time	Username	Problem	Language	Result	Execution time	Memory
928768		Foolestboy	Split the sequence (APIO14_sequence)	C++14	71 / 100	50 ms	131072 KiB

sequence

#include <bits/stdc++.h>

#define SQR(x)    (1LL * ((x) * (x)))
#define MASK(i)   (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1)
#define fi        first
#define se        second
#define pb        push_back
#define all(x)    x.begin(), x.end()
#define rall(x)   x.rbegin(), x.rend()
#define sz(s)     (int)s.size()
#define prev      __prev
#define next      __next
#define left      __left
#define right     __right

#define mp make_pair
#define pii pair<int, int>
#define pll pair<ll, ll>
#define vi vector<int>
#define vll vector<ll>

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

using namespace std;

const int mod = 1e9 + 7;
const int INF = 1e9 + 7;
const ll INFLL = (ll)2e18 + 7LL;
const ld PI = acos(-1);

const int dx[] = {1, -1, 0, 0, -1, 1, 1, -1};
const int dy[] = {0, 0, 1, -1, -1, -1, 1, 1};

template<class BUI, class TRONG>
    bool minimize(BUI &x, const TRONG y){
        if(x > y){
            x = y;
            return true;
        } else return false;
    }
template<class BUI, class TRONG>
    bool maximize(BUI &x, const TRONG y){
        if(x < y){
            x = y;
            return true;
        } else return false;
    }

/* Author : Bui Nguyen Duc Trong, Luong Van Chanh High School for the gifted*/
/* Template is copied by Trong */

                           /** Losing in Provincial Contests **/
                                    /** TRYING HARDER**/
                                   /**      ORZ     **/

/* -----------------[ MAIN CODE GOES HERE ]----------------- */

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int N = 1e5 + 10;

int n, k;
int a[N];

struct Line{
    ll a, b;

    Line() : a(0), b(0) {}

    Line(ll a, ll b) : a(a), b(b) {}

    ll f(ll x) { return a * x + b; }

};

struct ConvexHullTrick{
    vector<Line> vec;
    int iter = 0;

    ld inter(Line A, Line B){
        return (ld)(A.b - B.b) / (B.a - A.a);
    }

    void insertLine(Line l){
        if(!vec.empty() && l.a == vec.back().a) maximize(vec.back().b, l.b);
        else{
            while(sz(vec) >= 2 && inter(l, vec.back()) <= inter(vec.back(), vec[sz(vec) - 2])) vec.pop_back();
            vec.push_back(l);
        }
    }

    ll query(ll x){
        minimize(iter, sz(vec) - 1);
        while(iter + 1 < sz(vec) && vec[iter + 1].f(x) >= vec[iter].f(x)) ++iter;
        return vec[iter].f(x);
    }

} cht[202];

ll f[N][202];

void solve(){
    cin >> n >> k;
    for(int i = 1; i <= n; i++){
        cin >> a[i]; a[i] += a[i - 1];
    }
    for(int j = 1; j <= k; j++){
        for(int i = 1; i <= n; i++){
            cht[j - 1].insertLine(Line(a[i - 1], f[i - 1][j - 1] - 1LL * a[i - 1] * a[i - 1]));
            f[i][j] = cht[j - 1].query(a[i]);
        }
    }
    int r = n;
    ll cur = f[n][k];
    vector<int> ans;
    for(int i = k; i >= 1; i--){
        for(int j = r; j >= 2; j--){
            if(f[j - 1][i - 1] + 1LL * (a[r] - a[j - 1]) * a[j - 1] == f[r][i]){
                ans.push_back(j - 1);
                r = j - 1;
                break;
            }
        }
    }
    cout << f[n][k] << '\n';
    reverse(all(ans));
    for(int x : ans) cout << x << ' '; cout << '\n';
}
/*
7 3
4 1 3 4 0 2 3
*/

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

    const bool multitest = 0;
    int tt = 1; if(multitest) cin >> tt;

    while( tt-- ){

        solve();

    }

    return 0;
}

Compilation message (stderr)

sequence.cpp: In function 'void solve()':
sequence.cpp:131:5: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  131 |     for(int x : ans) cout << x << ' '; cout << '\n';
      |     ^~~
sequence.cpp:131:40: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
  131 |     for(int x : ans) cout << x << ' '; cout << '\n';
      |                                        ^~~~
sequence.cpp:118:8: warning: unused variable 'cur' [-Wunused-variable]
  118 |     ll cur = f[n][k];
      |        ^~~

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