Submission #966621

#	Time	Username	Problem	Language	Result	Execution time	Memory
966621		Trisanu_Das	Discharging (NOI20_discharging)	C++17	100 / 100	103 ms	25808 KiB

Discharging

#include <bits/stdc++.h>
#define int long long
using namespace std;
 
const int N = 1e6 + 11;
int a[N], dp[N];
int m[N], c[N], l, r;
 
int floor_div(int a, int b){
	return a / b - (a % b != 0 && a < 0);
}
 
int interX(int m1, int c1, int m2, int c2){
	return floor_div(c2 - c1, m1 - m2);
}
 
void add(int _m, int _c){
	while(r - l >= 2 && interX(m[r - 2], c[r - 2], _m, _c) <= interX(m[r - 2], c[r - 2], m[r - 1], c[r - 1])) r--;
	m[r] = _m, c[r] = _c; r++;
}
 
int qry(int x){
	while(r - l >= 2 && m[l] * x + c[l] >= m[l + 1] * x + c[l + 1]) l++;
	return m[l] * x + c[l];
}
 
int32_t main(){
	cin.tie(0); cout.tie(0)->sync_with_stdio(false);
	int n; cin >> n;
	for(int i = 0; i < n; i++) cin >> a[i];
	for(int i = 1; i < n; i++) a[i] = max(a[i - 1], a[i]);
	memset(dp, 0x3f, sizeof(dp)); dp[0] = 0;
	for(int i = 0; i < n; i++){
		add(-i, dp[i]);
		dp[i + 1] = a[i] * n + qry(a[i]); 
	}
	cout << dp[n] << endl;
}

• Subtask 1: 9 / 9
• Subtask 2: 13 / 13
• Subtask 3: 25 / 25
• Subtask 4: 11 / 11
• Subtask 5: 14 / 14
• Subtask 6: 28 / 28