Submission #203038

#	Time	Username	Problem	Language	Result	Execution time	Memory
203038		a1_N	Bigger segments (IZhO19_segments)	C++14	0 / 100	5 ms	380 KiB

segments

#include <bits/stdc++.h>

#define F first
#define S second

using namespace std;

const int N = (int)5e5 + 5;
const long long M = (long long)5e14;
    
int n,a[N];

long long pref[N];

pair<int,long long> dp[N];

map<int,int> Pos;

struct tree{
	tree *left,*right;
	int mx;
	tree(): left(NULL), right(NULL), mx(0) {}
}; 

tree *root = new tree();

int get_mx(tree *t){
	return (t != NULL) ? (t->mx) : 0;
}

void upd(tree *t,long long tl,long long tr,long long pos,int val){
	if(tl == tr){
		t->mx = val;
		return;
	}
	long long tm = (tl + tr) / 2;
	if(pos <= tm){
		if(t->left == NULL) t->left = new tree();
		upd(t->left,tl,tm,pos,val);		
	}
	else{
		if(t->right == NULL) t->right = new tree();
		upd(t->right,tm + 1,tr,pos,val);	
	}
	t->mx = max(get_mx(t->left),get_mx(t->right));
}

int get(tree *t,long long tl,long long tr,long long l,long long r){
	if(l <= tl && tr <= r) return t->mx;
	if(l > tr || r < tl) return 0;
	long long tm = (tl + tr) / 2;
	int mx1 = (t->left != NULL) ? get(t->left,tl,tm,l,r) : 0;
	int mx2 = (t->right != NULL) ? get(t->right,tm + 1,tr,l,r) : 0;
	return max(mx1,mx2);
}

int main(){
	ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	cin >> n;
	for(int i = 1; i <= n; i++){
		cin >> a[i];
		pref[i] = pref[i - 1] + a[i];
	}
	dp[1] = {1,a[1]};
	upd(root,1,M,pref[1] + dp[1].S,dp[1].F);
	Pos[dp[1].F] = 1;
	for(int i = 2; i <= n; i++){
		dp[i] = {dp[i - 1].F,dp[i - 1].S + a[i]};
		int cur = get(root,1,M,1,pref[i]);
	    dp[i] = {cur + 1,pref[i] - pref[Pos[cur]]};
		/* pref[i] - pref[j] >= dp[j].S 
			pref[i] >= pref[j] + dp[j].S

			1) we update value in position pref[j] + dp[j].S
			2) when we want to find answer satisfying condition for this position we use segment tree
		*/
		upd(root,1,M,pref[i] + dp[i].S,dp[i].F);
		Pos[dp[i].F] = i;	
	}
	cout << dp[n].F;
	return 0;
}

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