Submission #172973

#	Time	Username	Problem	Language	Result	Execution time	Memory
172973		LinusTorvaldsFan	Bigger segments (IZhO19_segments)	C++14	73 / 100	865 ms	262148 KiB

segments

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

struct Node{
	pair<int,int>val;
	ll l, r;
	Node*left;
	Node*right;
	Node(ll _l, ll _r) {
		val={0,0};
		l=_l;
		r=_r;
		left=nullptr;
		right=nullptr;
	}
};

pair<int,int>get_val(Node *root){
	if(root==nullptr)return make_pair(0,0);
	return root->val;
}

void update(Node *root, ll p, int x, int y) {
	if(root->l==p && root->r==p){
		root->val=max(make_pair(x,y),root->val);
		return;
	}
	ll m=(root->l+root->r)/2;
	if(root->l<=p&&p<=m){
		if(root->left==nullptr){
			root->left=new Node(root->l,m);
		}
		update(root->left,p,x,y);
	}
	else{
		if(root->right==nullptr){
			root->right=new Node(m+1,root->r);
		}
		update(root->right,p,x,y);
	}
	root->val=max(get_val(root->left),get_val(root->right));
}

pair<int,int> get(Node *root, ll l, ll r){
	if(l>root->r || root->l>r) {
		return {0,0};
	}
	if(l<=root->l && root->r<=r){
		return root->val;
	}
	pair<int,int> ans={0,0};
	if(root->right!=nullptr){
		ans=max(ans,get(root->right,l,r));
	}
	if(root->left!=nullptr){
		ans=max(ans,get(root->left,l,r));
	}
	return ans;
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int n;
	cin>>n;
	vector<int>a(n);
	for(int i=0;i<n;i++)cin>>a[i];
	
	vector<ll>pr(n+1);
	for(int i=0;i<n;i++)pr[i+1]=pr[i]+a[i];
	vector<int>ans(n);
	vector<ll> ans_sum(n);
	ll sum=0;
	for(int i=0;i<n;i++){
		sum+=a[i];
		ans_sum[i]=sum;
		ans[i]=1;
	}
	Node *tree=new Node(0,5e14);
	update(tree,ans_sum[0]+pr[1],ans[0],0);
	for(int i=1;i<n;i++){
		if(n<=100){
		for(int j=i-1;j>=0;j--){
			if(pr[i+1]>=ans_sum[j]+pr[j+1]){
				if(ans[i]<ans[j]+1){
					ans[i]=ans[j]+1;
					ans_sum[i]=pr[i+1]-pr[j+1];
				}
			}
		}
		//cout<<ans[i]<<" ";
		//cout<<ans_sum[i]<<" ";
		//cout<<endl;
		}
		else{
		auto t=get(tree,0,pr[i+1]);
		if(pr[i+1]>=ans_sum[t.second]+pr[t.second+1]){
			if(ans[i]<t.first+1){
				ans[i]=t.first+1;
				ans_sum[i]=pr[i+1]-pr[t.second+1];
			}	
		}
		update(tree,ans_sum[i]+pr[i+1],ans[i],i);
		}
		//cout<<ans[i]<<" ";
		//cout<<ans_sum[i]<<" ";
		//cout<<endl;
	}
	cout<<ans[n-1];
	return 0;
}

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