Submission #867771

#	Time	Username	Problem	Language	Result	Execution time	Memory
867771		dio_2	Hacker (BOI15_hac)	C++17	40 / 100	1008 ms	30884 KiB

hac

#include<bits/stdc++.h>
using namespace std;

const int MAX_N = 12 * 500'000;

int ST[MAX_N];

int main(){
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	for(int i = 1;i <= MAX_N;i++) ST[i] = -(int)1e9;
	
	int N;
	cin >> N;
	
	const int NN = 3 * N;
	
	vector<int> A(N);
	for(int &x : A) cin >> x; // A[i] <= 2000

	for(int i = 0;i < N;i++) A.push_back(A[i]);
	for(int i = 0;i < N;i++) A.push_back(A[i]);
	
	vector<array<int, 3>> wids;
	auto add = [&](int s, int l, int r)->void{
		wids.push_back({s, l, r});
	};
	
	int K = (N + 1) / 2;
	int sum = 0;
	for(int i = 0;i < K;i++){
		sum += A[N-K+i+1];
	}
	
	add(sum, N-K+1, N);
	
	for(int i = N + 1;i < 3 * N;++i){
		sum += A[i];
		sum -= A[i - K];
		add(sum, i - K + 1, i);
	}
	
	vector<int> in(NN, -1), out(NN, -1);
	vector<int> sums;
	int id = 0;
	for(auto [s, l, r] : wids){
		sums.push_back(s);
		swap(l, r);
		if(in[l] == -1) in[l] = id;
		if(out[r] == -1 && in[r] != -1) out[r] = id;
		++id;
	}
	
	int ans = 0;
	
	for(int i = 0;i < NN;i++){
		int res = 1000 * NN;
		if(in[i] == -1 || out[i] == -1) continue;
		for(int j = in[i];j <= out[i];j++) res = min(res, sums[j]);
		ans = max(ans, res);
	}
	
	cout << ans << '\n';
	
	return 0;
}

Compilation message (stderr)

hac.cpp: In function 'int main()':
hac.cpp:12:38: warning: iteration 5999999 invokes undefined behavior [-Waggressive-loop-optimizations]
   12 |  for(int i = 1;i <= MAX_N;i++) ST[i] = -(int)1e9;
      |                                ~~~~~~^~~~~~~~~~~
hac.cpp:12:18: note: within this loop
   12 |  for(int i = 1;i <= MAX_N;i++) ST[i] = -(int)1e9;
      |                ~~^~~~~~~~

• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 0 / 20
• Subtask 4: 0 / 40