Submission #1156419

#	Time	Username	Problem	Language	Result	Execution time	Memory
1156419		agrim_09	Split the sequence (APIO14_sequence)	C++20	71 / 100	2098 ms	173380 KiB

sequence

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
template <class T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define endl '\n';
#define fastio ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define py cout << "YES" << endl;
#define pn cout << "NO" << endl;
#define pb push_back
#define int long long
typedef long double lld;
#define double lld
typedef long long ll;
typedef unsigned long long ull;
const ll inf = 1e18;
const ll mod = 1e9+7;
const int N = 2e5;
vector<int>primes = {2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97};

void judge(){
    srand(time(NULL));
    #ifndef ONLINE_JUDGE
    freopen("1.txt","r",stdin);
    freopen("2.txt","w",stdout);
    freopen("Error.txt", "w", stderr);
    #define debug(x...) cerr << #x <<" = "; _print(x); cerr << endl;
    #else
    #define debug(x...)
    #endif
}

void usaco(string s) {
    freopen((s + ".in").c_str(),"r",stdin);
    freopen((s + ".out").c_str(),"w",stdout);
}

struct line {
	mutable int m, c, p;
    int pos;
	bool operator<(const line& l) const { return m < l.m; }
	bool operator<(int x) const { return p < x; }
};
// Returns max for a convex hull
struct LineContainer : multiset<line, less<>> {
	// (for doubles, use inf = 1/.0, ceil(a,b) = a/b)
	int div(int a, int b) { // floored division
		return a / b - ((a ^ b) < 0 && a % b);
	}

    bool isect(iterator x, iterator y) {
		if (y == end()){
            x -> p = inf;
            return false;
        }
		if (x->m==y->m){
			x->p = -1*inf;
            if (x->c > y->c) {
                x->p = inf;
            }
        }
		else{
            x->p = div(y->c - x->c, x->m - y->m);
        }
		return x->p >= y->p;
	}
	void add(int m, int c, int idx) {
		auto it = insert({m, c, 0, idx}) , next = it++, prev = next;
		while (isect(next, it)){
            it = erase(it);
        }
		if (prev != begin() && isect(--prev, next)){
            isect(prev, next = erase(next));
        }
		while ((next = prev) != begin() && (--prev)->p >= next->p){
            isect(prev, erase(next));
        }
	}
	pair<int,int> query(int x) {
		auto l = *lower_bound(x);
		return {l.m * x + l.c,l.pos};
	}
};



signed main(){
    fastio; //judge();
    int n,k; cin >> n >> k;
    k++;
    vector<int>a(n);
    for(auto &x : a) cin >> x;
    int sum = accumulate(a.begin(),a.end(),0);

    vector<int>dp1(n);
    vector<vector<int>>pos(n,vector<int>(k+1,-1));
    vector<int>pref(n);
    int curr = 0;
    for(int i = 0;i<n;i++){
        curr += a[i];
        dp1[i] = curr*curr;
        pos[i][1] = 0;
        pref[i] = curr;
    }
    vector<int>dp2(n);

    for(int kx = 2;kx<=k;kx++){
        LineContainer cht;
        for(int i = kx-2;i<=kx-2;i++){
            cht.add(2*pref[i],-1*(pref[i]*pref[i] + dp1[i]),i);
        }
        for(int i = kx-1;i<n;i++){
            curr = a[i];
            pair<int,int>tmp = cht.query(pref[i]);
            dp2[i] = pref[i]*pref[i] - 1*tmp.first;
            pos[i][kx] = tmp.second;
            cht.add(2 * pref[i], -1 * (pref[i] * pref[i] + dp1[i]), i);
        }
        dp1 = dp2;
    }
    cout << (sum*sum - dp1[n-1])/2 << endl;
    int num = n-1;
    vector<int>ordering;
    for(int i = k;i>=2;i--){
        ordering.pb(pos[num][i]+1);
        num = pos[num][i];
    }
    reverse(ordering.begin(),ordering.end());
    for(auto x : ordering)
        cout << x << ' ';
}

Compilation message (stderr)

sequence.cpp: In function 'void judge()':
sequence.cpp:27:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |     freopen("1.txt","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~
sequence.cpp:28:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   28 |     freopen("2.txt","w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~
sequence.cpp:29:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   29 |     freopen("Error.txt", "w", stderr);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
sequence.cpp: In function 'void usaco(std::string)':
sequence.cpp:37:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |     freopen((s + ".in").c_str(),"r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
sequence.cpp:38:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |     freopen((s + ".out").c_str(),"w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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