Submission #1270621

#	Time	Username	Problem	Language	Result	Execution time	Memory
1270621		thdh__	Hacker (BOI15_hac)	C++20	100 / 100	187 ms	143320 KiB

hac

#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define eb emplace_back
#define pu push
#define ins insert
#define fi first
#define se second
#define all(a) a.begin(),a.end()
#define bruh ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define fu(x,a,b) for (auto x=a;x<=b;x++)
#define fd(x,a,b) for (auto x=a;x>=b;x--)
#define int ll

using namespace std;
//mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());

/*
Competitive Programming notes that I need to study & fix my dumbass self:

1. Coding:
- Always be sure to check the memory of arrays (maybe use vectors), for loops
- Always try to maximize the memory if possible, even if you are going for subtasks
- Do not exploit #define int long long, it will kill you

2. Stress: 
- Always try generating big testcases and try if they run

3. Time management:
- Don't overcommit or undercommit, always spend a certain amount of time to think a problem, don't just look at it and say I'm fucked
- Do not spend too much time coding brute-force solutions, they should be easily-codable solutions that don't take up too much time

Time management schedule:
Offline / LAH days (4 problems - 3h):
15' thinking of solution / idea
1. no idea: skip
2. yes idea: continue thinking for <= 15'

+ implementing: <= 20'
+ brute-force: <= 5'
+ test generator: <= 5'

I hate offline because I am dumb
*/

typedef pair<int, int> ii;
const int N = 1e6+5;
const int M = 20;
const int B = 750;
const int mod = 1e9+7;
const int inf = 1e18;
using cd = complex<double>;
const long double PI = acos(-1);
int power(int a,int b) {ll x = 1;if (a >= mod) a%=mod; while (b) {if (b & 1) x = x*a % mod;a = a*a % mod;b>>=1;}return x;} 

int n, m;
int a[N];
int pref[N];
int block[N];
int st[N][M], lg[N];

void build() 
{
	lg[1] = 0;
	for (int i = 2; i <= n; i++) lg[i] = lg[i/2] + 1;
	for (int i = 1; i <= 2*n-m+1; i++) st[i][0] = block[i];
	for (int j = 1; j < M; j++) for (int i = 1; i + (1<<j) - 1 <= 2*n-m+1; i++) st[i][j] = min(st[i][j-1], st[i+(1<<(j-1))][j-1]);
}

int get(int l, int r) 
{
	int i = lg[r-l+1];
	return min(st[l][i], st[r-(1<<i)+1][i]);
}

void solve()
{
	cin>>n;
	for (int i = 1; i <= n; i++) 
	{
		cin>>a[i]; a[i+n] = a[i];
	}
	for (int i = 1; i <= 2*n; i++) pref[i] = pref[i-1] + a[i];
	m = (n+1) / 2;
	for (int i = 1; i <= 2*n-m+1; i++) block[i] = pref[i+m-1] - pref[i-1];
	build();
	// for (int i = 1; i <= 2*n-m+1; i++) cout<<block[i]<<" ";
	// cout<<endl;
	int ans = 0;
	for (int i = m; i <= 2*n-m+1; i++) 
	{
		ans = max(ans, get(i-m+1, i));
	}
	cout<<ans;
}

/*
Go through the mistakes you usually make and revise your code, for god's sake...
*/

signed main()
{
	bruh
	//freopen("input.inp","r",stdin);
	//freopen("output.inp","w",stdout);
	int t = 1;
	// cin>>t;
	while (t--)
	{
		solve();
		cout<<"\n";
	}
}

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