Submission #23647

#	Time	Username	Problem	Language	Result	Execution time	Memory
23647		SYury	Split the sequence (APIO14_sequence)	C++11	71 / 100	2000 ms	86556 KiB

sequence

#include<bits/stdc++.h>

using namespace std;
typedef long long lint;
typedef long double ldb;
typedef unsigned long long uli;

#define X first
#define Y second
#define F(i, l, r) for(int i = l; i != r; i++)
#define Df(i, l, r) for(int i = l; i != r; i--)
#define I(i, a) for(auto i : a)
#define pb push_back
#define rs resize
#define mk make_pair
#define asg assign
#define all(x) x.begin(),x.end()
#define ret return
#define cont continue
#define brk break
#define ins insert
#define era erase
#define fi0(x) memset(x, 0, sizeof(x))
#define finf(x) memset(x, 127, sizeof(x))
#define acpy(y, x) memcpy(y, x, sizeof(y))
#define y1 adjf
#define tm dhgdg

const int MAXN = 1e5 + 3;
const int MAXK = 2e2 + 2;
const ldb eps = 1e-16;

int pr[MAXN][MAXK];
int a[MAXN];
int pref[MAXN];
lint sqp[MAXN];
int n, k;

struct line{
	lint b;
	int id;
	line(){}
	line(lint pb, int pid):b(pb),id(pid){}
	lint f(int x){
		ret pref[id] * 1ll * x + b;
	}
	lint k(){
		ret pref[id];
	}
};

struct convex_hull{
	line l[MAXN];
	int sz = 0;
	int ptr = 0;
	void add_line(line curr){
		while(sz > 0 && l[sz - 1].k() == curr.k() && l[sz - 1].b < curr.b){sz--;}
		if(sz > 0 && l[sz - 1].k() == curr.k() && l[sz - 1].b >= curr.b){
			ptr = min(ptr, sz - 1);
			ret;
		}
		while(sz >= 2){
			line l1 = l[sz - 1], l2 = l[sz - 2];
			//lint f1 = (l1.k - l2.k) * (l1.b - curr.b), f2 = (l2.b - l1.b) * (curr.k - l1.k);
			ldb f2 = (l2.b - l1.b)/((ldb)l1.k() - l2.k()), f1 = (l1.b - curr.b)/((ldb)curr.k() - l1.k());
			if(f2 < f1 - eps)brk;
			sz--;
		}
		l[sz++] = curr;
		ptr = min(ptr, sz - 1);
	}
	pair<int, lint> get(int x, int cid){
		if(sz == 0)ret mk(-1, 0);
		ptr = min(ptr, sz - 1);
		while(ptr < sz - 1 && l[ptr + 1].id < cid && l[ptr].f(x) <= l[ptr + 1].f(x))ptr++;
		if(l[ptr].id >= cid)ret mk(-1, 0);
		ret mk(l[ptr].id, l[ptr].f(x));
	}
	void clear(){
		sz = 0;
		ptr = 0;
	}
};

convex_hull ch[2];

void restore(int i, int j){
	while(i >= 0){
		printf("%d ", i + 1);
		i = pr[i][j]; j--;
	}
}

lint dcp[MAXN];

int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	scanf("%d%d", &n, &k);
	F(i, 0, n)scanf("%d", &a[i]);
	F(i, 0, n)pref[i] = a[i] + ((i == 0) ? 0 : pref[i - 1]);
	k++;
	F(i, 0, n)sqp[i] = pref[i] * 1ll * pref[i];
	F(i, 0, n)
		F(j, 1, k + 1)
			pr[i][j] = -2;
	F(i, 0, n)pr[i][1] = -1;
	F(i, 0, n)ch[0].add_line(line(-sqp[i], i));
	int tc = 1;
	F(j, 2, k + 1){
		ch[tc].clear();
		F(i, j - 1, n){
			pair<int, lint> tmp = ch[1 - tc].get(pref[i], i);
			if(tmp.X == -1){cont;}
			dcp[i] = tmp.Y;
			pr[i][j] = tmp.X;
			ch[tc].add_line(line(dcp[i] - sqp[i], i));
		}
		tc = 1 - tc;
	}
	printf("%lld\n", dcp[n - 1]);
	restore(pr[n - 1][k], k - 1);
	ret 0;
}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:99:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &n, &k);
                       ^
sequence.cpp:100:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  F(i, 0, n)scanf("%d", &a[i]);
                              ^

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