oj.uz

Submission #26469

# Submission time Handle Problem Language Result Execution time Memory
26469 2017-07-01T06:03:14 Z zscoder Three Friends (BOI14_friends) C++14
35 / 100
 356 ms 20908 KB 
#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define mp make_pair
#define pb push_back

typedef long long ll;
typedef pair<int,int> ii;
typedef vector<int> vi;
typedef long double ld; 

const int INF = 1e9 + 7;
const int MOD = 1e9 + 9;
const int C = 2017;

ll modpow(ll a, ll b)
{
	if(b<0) b+=(MOD-1);
	ll r= 1;
	while(b)
	{
		if(b&1) r = (r*a)%MOD;
		a=(a*a)%MOD;
		b>>=1;
	}
	return r;
}

ll inv(ll x)
{
	return modpow(x, MOD - 2);
}

ll invC;

ll dp[2000001];

ll hsh(int l, int r)
{
	if(r<l) return 0;
	r++; l++;
	return ((dp[r] - dp[l-1])%MOD+MOD)%MOD;
}

int main()
{
	ios_base::sync_with_stdio(0); cin.tie(0);
	//freopen("friend.in", "r", stdin);
	invC = inv(C);
	int n; string s;
	cin >> n >> s;
	if(n%2==0)
	{
		cout << "NOT POSSIBLE";
		return 0;
	}
	int l = n/2;
	vi pos;
	//string a = s.substr(0, l);
	//string b = s.substr(l, l);
	//if(a == b) pos = n - 1;
	bool started = false;
	bool flag = true; char theletter = '$';
	ll CMOD = modpow(C,l+1);
	for(int i = 1; i <= n; i++)
	{
		dp[i] = (dp[i-1] + ll(s[i-1]-'A'+1)*modpow(C, n - i))%MOD;
	}
	for(int i = 0; i < n; i++) //it's placed at pos i
	{
		if(started)
		{
			if(s[i] != theletter) flag = false;
		}
		if(i < l)
		{
			ll h1 = hsh(0,i-1);
			ll h2 = hsh(i+1,l);
			h2 = (h2*C)%MOD;
			h1 += h2;
			h1%=MOD;
			if(h1 == (hsh(l+1,n-1)*CMOD)%MOD)
			{
				pos.pb(i);
				if(!flag)
				{
					cout << "NOT UNIQUE";
					return 0;
				}
				if(!started)
				{
					started = true;
					theletter = s[i];
				}
			}
		}
		if(i == l)
		{
			if(hsh(0,l-1)==(hsh(l+1,n-1)*CMOD)%MOD)
			{
				pos.pb(i);
				if(!flag)
				{
					cout << "NOT UNIQUE";
					return 0;
				}
				if(!started)
				{
					started = true;
					theletter = s[i];
				}
			}
		}
		if(i > l)
		{
			ll h1 = hsh(l,i-1);
			ll h2 = hsh(i+1,n-1);
			h1=(h1*invC)%MOD;
			h1=(h1+h2)%MOD;
			if(hsh(0,l-1)==(h1*CMOD)%MOD)
			{
				pos.pb(i);
				if(!flag)
				{
					cout << "NOT UNIQUE";
					return 0;
				}
				if(!started)
				{
					started = true;
					theletter = s[i];
				}
			}
		}
	}
	if(pos.empty())
	{
		cout << "NOT POSSIBLE"; return 0;
	}
	/*
	char commonletter = s[pos[0]];
	for(int i = 0; i < pos.size(); i++)
	{
		if(s[pos[i]] != commonletter)
		{
			cout << "NOT POSSIBLE"; return 0;
		}
	}
	*/
	int cnt = 0;
	for(int i = 0; i < pos[0]; i++)
	{
		if(cnt >= l) break;
		cout << s[i];
		cnt++;
	}
	for(int i = pos[0] + 1; i < n; i++)
	{
		if(cnt >= l) break;
		cout << s[i];
		cnt++;
	}
}

Subtask #1
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 17804 KB Output is correct
2 Correct 0 ms 17804 KB Output is correct
3 Correct 0 ms 17804 KB Output is correct
4 Correct 0 ms 17804 KB Output is correct
5 Correct 0 ms 17804 KB Output is correct
6 Correct 0 ms 17804 KB Output is correct
7 Correct 0 ms 17804 KB Output is correct
8 Correct 0 ms 17804 KB Output is correct
9 Correct 0 ms 17804 KB Output is correct
10 Correct 0 ms 17804 KB Output is correct
11 Correct 0 ms 17804 KB Output is correct
12 Correct 0 ms 17804 KB Output is correct
13 Correct 0 ms 17804 KB Output is correct
14 Correct 0 ms 17804 KB Output is correct
15 Correct 0 ms 17804 KB Output is correct
16 Correct 0 ms 17804 KB Output is correct
17 Correct 0 ms 17804 KB Output is correct
18 Correct 0 ms 17804 KB Output is correct
19 Correct 0 ms 17804 KB Output is correct
20 Correct 0 ms 17804 KB Output is correct
21 Correct 0 ms 17804 KB Output is correct
22 Correct 0 ms 17804 KB Output is correct
23 Correct 0 ms 17804 KB Output is correct
24 Correct 0 ms 17804 KB Output is correct
25 Correct 0 ms 17804 KB Output is correct
26 Correct 0 ms 17804 KB Output is correct
27 Correct 0 ms 17804 KB Output is correct
28 Correct 0 ms 17804 KB Output is correct
29 Correct 0 ms 17804 KB Output is correct
30 Correct 0 ms 17804 KB Output is correct
31 Correct 0 ms 17804 KB Output is correct
32 Correct 0 ms 17804 KB Output is correct
33 Correct 0 ms 17804 KB Output is correct
34 Correct 0 ms 17804 KB Output is correct
35 Correct 0 ms 17804 KB Output is correct
36 Correct 0 ms 17804 KB Output is correct
37 Correct 0 ms 17804 KB Output is correct
38 Correct 0 ms 17804 KB Output is correct
39 Correct 0 ms 17804 KB Output is correct
40 Correct 0 ms 17804 KB Output is correct
41 Correct 0 ms 17804 KB Output is correct
42 Correct 0 ms 17804 KB Output is correct
43 Correct 0 ms 17804 KB Output is correct
44 Correct 0 ms 17804 KB Output is correct
45 Correct 0 ms 17804 KB Output is correct
46 Correct 0 ms 17804 KB Output is correct
47 Correct 0 ms 17804 KB Output is correct
48 Correct 0 ms 17804 KB Output is correct
49 Correct 0 ms 17804 KB Output is correct
50 Correct 0 ms 17804 KB Output is correct
51 Correct 0 ms 17804 KB Output is correct
52 Correct 0 ms 17804 KB Output is correct
53 Correct 0 ms 17804 KB Output is correct
54 Correct 0 ms 17804 KB Output is correct

Subtask #2
0 / 65.0

# Verdict Execution time Memory Grader output
1 Runtime error 356 ms 20908 KB Execution killed because of forbidden syscall writev (20)
2 Halted 0 ms 0 KB -