Submission #370541

#	Time	Username	Problem	Language	Result	Execution time	Memory
370541		fhvirus	Bigger segments (IZhO19_segments)	C++17	0 / 100	1 ms	364 KiB

segments

// Knapsack DP is harder than FFT.
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii; typedef pair<ll, ll> pll;
#define ff first
#define ss second
#define pb emplace_back
#define FOR(i,n) for(int i = 0; i < (n); ++i)
#define FOO(i,a,b) for(int i = (a); i <= (b); ++i)
#define AI(x) (x).begin(),(x).end()
template<typename I> bool chmax(I &a, I b){ return a < b ? (a = b, true) : false;}
template<typename I> bool chmin(I &a, I b){ return a > b ? (a = b, true) : false;}
#ifdef OWO
#define debug(args...) LKJ("[ " + string(#args) + " ]", args)
void LKJ(){ cerr << endl;}
template<typename I, typename...T> void LKJ(I&&x, T&&...t){ cerr<<x<<", ", LKJ(t...);}
template<typename I> void DE(I a, I b){ while(a < b) cerr<<*a<<" \n"[next(a)==b], ++a;}
#else
#define debug(...) 0
#define DE(...) 0
#endif
#ifndef OWO
#pragma GCC optimize("Ofast")
#endif
const int N = 5e5 + 225;
int n, a[N];
ll s[N];

int32_t main(){
	ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	cin >> n; FOO(i,1,n) cin >> a[i];
	FOO(i,1,n) s[i] = s[i-1] + a[i];

	vector<int> dp(n + 1, 0);
	vector<ll> mn(n + 1, 4e18);
	mn[0] = 0;
	deque<int> sc;
	sc.pb(0);
	FOO(i,1,n){
		dp[i] = dp[i-1];
		mn[i] = mn[i-1] + a[i];
		int cursc = 0;
		for(int x = 0; x < sc.size(); ++x){
			int j = sc[x];
			ll sum = s[i] - s[j];
			if(sum < mn[j]) continue;
			if(dp[j] + 1 > dp[i]){
				dp[i] = dp[j] + 1;
				mn[i] = sum;
				cursc = j;
			} else if(dp[j] + 1 == dp[i]){
				if(chmin(mn[i], sum)) cursc = j;
			}
		}
		while(sc.size() and sc.back() > cursc) sc.pop_back();
		while(sc.size() and dp[sc.front()] < dp[i] - 1) sc.pop_front();
		sc.pb(i);
	}
	cout << dp[n] << '\n';

	return 0;
}

Compilation message (stderr)

segments.cpp: In function 'int32_t main()':
segments.cpp:44:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::deque<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |   for(int x = 0; x < sc.size(); ++x){
      |                  ~~^~~~~~~~~~~

• Subtask 1: 0 / 13
• Subtask 2: 0 / 14
• Subtask 3: 0 / 10
• Subtask 4: 0 / 36
• Subtask 5: 0 / 27