Submission #108151

#	Time	Username	Problem	Language	Result	Execution time	Memory
108151		RockyB	Split the sequence (APIO14_sequence)	C++14	100 / 100	498 ms	82492 KiB

sequence

/// In The Name Of God
 
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
 
#include <bits/stdc++.h>
 
#define f first
#define s second
 
#define pb push_back
#define pp pop_back
#define mp make_pair
 
#define sz(x) (int)x.size()
#define sqr(x) ((x) * 1ll * (x))
#define all(x) x.begin(), x.end()
 
#define Kazakhstan ios_base :: sync_with_stdio(0), cin.tie(0), cout.tie(0);
 
#define nl '\n'
#define ioi exit(0);
 
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
 
const int N = (int)1e5 + 7;
const int inf = (int)1e9 + 7;
const int mod = (int)1e9 + 7;
const ll linf = (ll)1e18 + 7;
 
const int dx[] = {-1, 0, 1, 0, 1, -1, -1, 1};
const int dy[] = {0, 1, 0, -1, 1, -1, 1, -1};
 
using namespace std;
 
int get_int() {
	char x = getchar();
	while (!isdigit(x)) x = getchar();
	int res = 0;
	while (isdigit(x)) res = res * 10 + x - '0', x = getchar();
	return res;
}
void out(int x) {
	if (x > 9) out(x / 10);
	putchar(x % 10 + '0');
}
 
struct line {
	int k, id;
	ll b;
	line() {}
	line(int k, ll b, int id) : k(k), b(b), id(id) {}
	ll get(int x) {
		return (ll)k * x + b;
	}
};
struct cht {	
	int ptr, sz;
	line v[N];
 
	inline double inter(line &a, line &b) {
		return (b.b - a.b) / (double)(a.k - b.k);
	}
	inline void add(line x) {
		/*int l = 2, r = sz, res = sz;
		while (l <= r) {
			int mid = l + r >> 1;
			if (inter(v[mid - 1], x) <= inter(v[mid - 1], v[mid])) res = mid - 1, r = mid - 1;
			else l = mid + 1;
		}
		sz = res;*/
		while (sz > 1 && inter(v[sz - 1], x) <= inter(v[sz - 1], v[sz])) --sz;
		v[++sz] = x;
	}
	inline line get(ll x) {
		ptr = min(ptr, sz);
		while (ptr < sz && v[ptr].get(x) <= v[ptr + 1].get(x)) ptr++;
		return v[ptr];
	}
	void clear() {
		sz = 0;
		ptr = 1;
	}
} t;
 
int n, k;
int a[N], s[N], p[N];
 
int now;
ll dp[2][N];
int opt[201][N];
 
bool upd(ll &x, ll y) {
	if (x < y) {
		x = y;
		return 1;
	}
	return 0;
}
 
int main() {
	#ifdef IOI2018
		freopen ("in.txt", "r", stdin);
	#endif
	n = get_int(), k = get_int();
	for (int i = 1; i <= n; i++) {
		a[i] = get_int();
		s[i] = a[i];
		p[i] = p[i - 1] + a[i];
	}
	for (int i = n; i >= 1; i--) {
		s[i] += s[i + 1];
	}
	for (int i = 1, p = 0; i <= n; i++) {
		p += a[i];
		dp[now][i] = (ll)p * s[i + 1];
	}
	for (int o = 2; o <= k; o++) {
		t.clear();
		int nxt = now ^ 1;
		for (int i = o - 1; i <= n; i++) {
			t.add({p[i - 1], dp[now][i - 1], i});
			line res = t.get(-s[i + 1]);
			opt[o][i] = res.id;
			dp[nxt][i] = res.get(-s[i + 1]) + (ll)p[i] * s[i + 1];
		}
		now ^= 1;
	}	
	ll ans = -linf;
	int ptr = -1;
	for (int i = 1; i < n; i++) {
		if (upd(ans, dp[now][i])) {
			ptr = i;
		}
	}
	printf ("%lld\n", ans);
	vector <int> res;
	for (int i = k; i >= 1; i--) {
		res.pb(ptr);
		ptr = opt[i][ptr] - 1;
	}	
	reverse(all(res));
	for (auto it : res) {
		out(it);
		putchar(' ');
	}
	ioi
}

Compilation message (stderr)

sequence.cpp: In constructor 'line::line(int, ll, int)':
sequence.cpp:52:5: warning: 'line::b' will be initialized after [-Wreorder]
  ll b;
     ^
sequence.cpp:51:9: warning:   'int line::id' [-Wreorder]
  int k, id;
         ^~
sequence.cpp:54:2: warning:   when initialized here [-Wreorder]
  line(int k, ll b, int id) : k(k), b(b), id(id) {}
  ^~~~

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