Submission #410349

#	Time	Username	Problem	Language	Result	Execution time	Memory
410349		NurstanDuisengaliev	3D Histogram (COCI20_histogram)	C++14	110 / 110	491 ms	39508 KiB

histogram

// Nurstan Duisengaliev(REALBOY)
// Respa Gold_2022
// IZHO GOLD_2022
// IOI_2022 
/*#pragma GCC target ("avx2")
#pragma GCC optimize ("Ofast")
#pragma GCC optimize ("unroll-loops")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimize("O3")*/                   
      
#include <bits/stdc++.h>
 
#define ll long long
#define all(x) x.begin(), x.end()
#define in insert
#define mp make_pair
#define F first
#define S second
#define ppf pop_front
#define pb push_back
#define ppb pop_back
#define pf push_front
#define pii pair <ll, ll>
#define boost() ios_base::sync_with_stdio(0), cin.tie(0)
#define sz(x) (int)x.size()
#define int ll
using namespace std;
 
const int N = (int)2e5 + 123;
const int mod = (int)1e9 + 7;
const ll INF = (ll)1e18 + 1;
int n, a[N], b[N];
ll ans = 0;
void Case1 (int l, int mid, int r) {
	int pos = mid, minia = mod, minib = mod;
	for (int i = mid; i >= l; i --) {
		minia = min (minia, a[i]);
		minib = min (minib, b[i]);
		while (pos < r && a[pos + 1] >= minia && b[pos + 1] >= minib) pos ++;
		ans = max (ans, minia * 1ll * minib * 1ll * (pos - i + 1));	
	}
}
vector <pii> d[N * 4];
vector <pii> line;
int ok[N * 4];
int intercept (pii a, pii b, pii c, pii d) {
	return (b.S - a.S) * (c.F - d.F) - (d.S - c.S) * (a.F - b.F);
}
void Build (int v, int l, int r) {
	if (l == r) {
		ok[v] = 0;
		d[v].pb (line[l]);
		return;
	}
	int mid = l + r >> 1;
	Build (v * 2, l, mid);
	Build (v * 2 + 1, mid + 1, r);	
	d[v] = d[v * 2];
	for (auto it : d[v * 2 + 1]) {
		while (sz (d[v]) >= 2 && intercept (d[v][sz (d[v]) - 1], it, d[v][sz (d[v]) - 1], d[v][sz (d[v]) - 2]) <= 0) {
			d[v].ppb ();
		}
		d[v].pb (it);
	}
	ok[v] = sz (d[v]) - 1;
}
void Build_CHT (int l, int mid, int r) {
	line.clear ();    
    int minib = mod;
	for (int i = mid + 1; i <= r; i ++) {
		minib = min (minib, b[i]);
		line.pb (mp (minib, minib * i));  
	}	
	for (int i = 1; i <= sz (line) * 4; i ++) d[i].clear ();
	Build (1, 0, sz (line) - 1);
}
ll Val (ll x, pii k) {
	return x * k.F + k.S;	
}
ll Get (int v, int l, int r, int nl, int nr, int x) {
	if (nl > r || l > nr) return 0ll;
	if (nl <= l && r <= nr) {
		while (ok[v] - 1 >= 0 && Val (x, d[v][ok[v] - 1]) >= Val (x, d[v][ok[v]])) ok[v] --;
		return Val (x, d[v][ok[v]]);			
	}
	int mid = l + r >> 1;
	return max (Get (v * 2, l, mid, nl, nr, x), Get (v * 2 + 1, mid + 1, r, nl, nr, x));
}
void Case2 (int l, int mid, int r) {
	int minia = mod, minib = mod, minio = mod, sl = mid, sr = mid;
	vector <pii> interval;
	for (int i = mid; i >= l; i --) {
		minia = min (minia, a[i]);
		minib = min (minib, b[i]);
		while (sr < r && a[sr + 1] >= minia) sr ++;
		while (sl <= r && minio > minib) {
			sl ++;
			minio = min (minio, b[sl]);
		}
		// sl....sr
		interval.pb (mp (sl - mid - 1, sr - mid - 1));
	}	
	Build_CHT (l, mid, r);
	minia = mod;
	for (int i = mid; i >= l; i --) {
		minia = min (minia, a[i]);
		// interval[mid - i]
		int L = interval[mid - i].F, R = interval[mid - i].S;
		if (L >= 0 &&  L <= R) {
			ans = max (ans, minia * 1ll * Get (1, 0, sz (line) - 1, L, R, 1 - i));
		}
	}
}
void calc (int l, int r, int t) {
	if (l > r) return;
	if (l == r) {
		ans = max (ans, a[l] * 1ll * b[l]);
		return;
	}
	int mid = (l + r - t) / 2;
	Case1 (l, mid, r);
	Case2 (l, mid, r);
	calc (l, mid, t);
	calc (mid + 1, r, t);	
} 
ll solve () {
	cin >> n;
	for (int i = 1; i <= n; i ++) {
		cin >> a[i] >> b[i];
	}		      
	ans = 0;
	calc (1, n, 0);
	reverse (a + 1, a + n + 1);
	reverse (b + 1, b + n + 1);
	calc (1, n, 1);
	return ans; 
}   	
 
main () {
//	freopen (".in", "r", stdin);
//	freopen (".out", "w", stdout);
	boost ();
	cout << solve ();
	return 0;	                                    
}

Compilation message (stderr)

histogram.cpp: In function 'void Build(long long int, long long int, long long int)':
histogram.cpp:55:14: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   55 |  int mid = l + r >> 1;
      |            ~~^~~
histogram.cpp: In function 'long long int Get(long long int, long long int, long long int, long long int, long long int, long long int)':
histogram.cpp:86:14: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   86 |  int mid = l + r >> 1;
      |            ~~^~~
histogram.cpp: At global scope:
histogram.cpp:139:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
  139 | main () {
      | ^~~~

• Subtask 1: 20 / 20
• Subtask 2: 90 / 90