Submission #801989

#	Time	Username	Problem	Language	Result	Execution time	Memory
801989		fatemetmhr	Giraffes (JOI22_giraffes)	C++17	32 / 100	1 ms	340 KiB

giraffes

// Be name khode //


#include <bits/stdc++.h>

using namespace std;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

typedef long long ll;
typedef long double ld;

#define all(x) x.begin(), x.end()
#define mp     make_pair
#define pb     push_back
#define fi     first
#define se     second

const int maxn5 = 8e3 + 5;

int a[maxn5], ind[maxn5];
bool rem[maxn5];


int main(){
	ios_base::sync_with_stdio(false); cin.tie(0);

	int n; cin >> n;
	for(int i = 0; i < n; i++){
		cin >> a[i];
		a[i]--;
		ind[a[i]] = i;
	}
	int tt = 500;
	int ans = n;
	while(tt--){
		int l = 0, r = n - 1;
		int ptl = 0, ptr = n - 1;
		int cur = 0;
		memset(rem, false, sizeof rem);
		for(int x = 0; x < n; x++){
			if(ind[ptl] == l && !rem[l]){
				ptl++;
				l++;
				continue;
			}
			if(ind[ptl] == r && !rem[r]){
				ptl++;
				r--;
				continue;
			}
			if(ind[ptr] == l && !rem[l]){
				ptr--;
				l++;
				continue;
			}
			if(ind[ptr] == r && !rem[r]){
				ptr--;
				r--;
				continue;
			}
			int ty1 = rng() % 2, ty2 = rng() % 2;
			//cout << "in " << tt << ' ' << ptl << ' ' << ptr << ' ' << l << ' ' << r << ' ' << ty1 << ' ' << ty2 << endl;
			if(ty1){
				if(!rem[ind[ptl]])
					cur++;
				rem[ind[ptl]] = true;
				ptl++;
			}
			else{
				if(!rem[ind[ptr]])
					cur++;
				rem[ind[ptr]] = true;
				ptr--;
			}
			if(ty2){
				if(!rem[l])
					cur++;
				rem[l] = true;
				l++;
			}
			else{
				if(!rem[r])
					cur++;
				rem[r] = true;
				r--;
			}
		}
		ans = min(ans, cur);
	}
	cout << ans << endl;
}

• Subtask 1: 10 / 10
• Subtask 2: 22 / 22
• Subtask 3: 0 / 27
• Subtask 4: 0 / 41