oj.uz

Submission #39341

# Submission time Handle Problem Language Result Execution time Memory
39341 2018-01-11T17:50:49 Z qoo2p5 Palindromes (APIO14_palindrome) C++14
100 / 100
 889 ms 17672 KB 
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;

const int INF = (int) 1e9 + 1e6 + 123;
const ll LINF = (ll) 1e18 + 1e9 + 123;
const ld EPS = (ld) 1e-7;
const ll MOD = (ll) 1e9 + 7;

#define sz(x) (int) (x).size()
#define mp(x, y) make_pair(x, y)
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define lb(s, t, x) (int) (lower_bound(s, t, x) - s)
#define ub(s, t, x) (int) (upper_bound(s, t, x) - s)
#define rep(i, f, t) for (int i = f; i < t; i++)
#define per(i, f, t) for (int i = f; i >= t; i--)

ll power(ll x, ll y, ll mod = MOD) {
    if (y == 0) {
        return 1;
    }
    if (y & 1) {
        return power(x, y - 1, mod) * x % mod;
    } else {
        ll tmp = power(x, y / 2, mod);
        return tmp * tmp % mod;
    }
}

template<typename A, typename B> bool mini(A &x, const B &y) {
    if (y < x) {
        x = y;
        return true;
    }
    return false;
}

template<typename A, typename B> bool maxi(A &x, const B &y) {
    if (y > x) {
        x = y;
        return true;
    }
    return false;
}

void add(ll &x, ll y) {
	x += y;
	if (x >= MOD) x -= MOD;
	if (x < 0) x += MOD;
}

ll mult(ll x, ll y) {
	return x * y % MOD;
}

void run();

#define TASK ""

int main() {
#ifdef LOCAL
    if (strlen(TASK) > 0) {
        cerr << "Reminder: you are using file i/o, filename: " TASK "!" << endl << endl;
    }
#endif
#ifndef LOCAL
    if (strlen(TASK)) {
        freopen(TASK ".in", "r", stdin);
        freopen(TASK ".out", "w", stdout);
    }
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
#endif
    cout << fixed << setprecision(12);
    run();
    return 0;
}

// == SOLUTION == //

vector<int> manaher(const string &s) {
	string t;
	for (char c : s) {
		t += '$';
		t += c;
	}
	t += '$';
	int n = sz(t);
	vector<int> res(n);
	int l = -1, r = -1;
	rep(i, 0, n) {
		int k = 1;
		if (i <= r) {
			k = min(r - i + 1, res[l + r - i]);
		}
		while (i - k >= 0 && i + k < n && t[i - k] == t[i + k]) {
			k++;
		}
		if (i + k - 1 > r) {
			l = i - k + 1;
			r = i + k - 1;
		}
		res[i] = k;
	}
	/*rep(i, 0, n) {
		int k = 1;
		while (i - k >= 0 && i + k < n && t[i - k] == t[i + k]) {
			k++;
		}
		res[i] = k;
	}*/
	return res;
}

vector<int> suff_arr(string s) {
	s += '$';
	int n = sz(s);
	vector<int> cl(n);
	rep(i, 0, n) {
		cl[i] = s[i];
	}
	vector<pair<pair<int, int>, int>> ids(n);
	vector<int> tmp(n);
	int A = max(n, 256);
	vector<int> cnt(A);
	for (int len = 1; len < n; len *= 2) {
		fill(all(cnt), 0);
		rep(i, 0, n) {
			int c = cl[(i + len) % n];
			cnt[c + 1]++;
		}
		rep(i, 1, A) {
			cnt[i] += cnt[i - 1];
		}
		rep(i, 0, n) {
			int c = cl[(i + len) % n];
			tmp[cnt[c]++] = i;
		}
		fill(all(cnt), 0);
		rep(i, 0, n) {
			int id = tmp[i];
			cnt[cl[id] + 1]++;
		}
		rep(i, 1, A) {
			cnt[i] += cnt[i - 1];
		}
		rep(i, 0, n) {
			int id = tmp[i];
			ids[cnt[cl[id]]++] = {{cl[id], cl[(id + len) % n]}, id};
		}
		
		int ptr = 0;
		rep(i, 0, n) {
			int j = i;
			cl[ids[i].second] = ptr;
			while (j + 1 < n && ids[j + 1].first == ids[j].first) cl[ids[++j].second] = ptr;
			ptr++;
			i = j;
		}
	}
	
	vector<int> res(n - 1);
	rep(i, 0, n - 1) {
		int pos = cl[i] - 1;
		assert(pos >= 0);
		res[pos] = i;
	}
	return res;
	
	/*int n = sz(s);
	vector<pair<string, int>> q(n);
	rep(i, 0, n) q[i] = {s.substr(i), i};
	sort(all(q));
	vector<int> res(n);
	rep(i, 0, n) res[i] = q[i].second;
	return res;*/
}

vector<int> get_lcp(const string &s, const vector<int> &arr) {
	int n = sz(s);
	assert(sz(s) == sz(arr));
	vector<int> res(n), pos(n);
	rep(i, 0, n) {
		pos[arr[i]] = i;
	}
	int k = 0;
	rep(i, 0, n) {
		if (k > 0) {
			k--;
		}
		
		int p = pos[i];
		if (p == n - 1) {
			k = 0;
		} else {
			int j = arr[p + 1];
			while (i + k < n && j + k < n && s[i + k] == s[j + k]) {
				k++;
			}
		}
		
		res[p] = k;
	}
	return res;
	/*int n = sz(s);
	vector<int> res(n);
	rep(i, 0, n - 1) {
		int k = 0;
		int p = arr[i];
		int q = arr[i + 1];
		while (p + k < n && q + k < n && s[p + k] == s[q + k]) k++;
		res[i] = k;
	}
	return res;*/
}

const int N = (int) 3e5 + 123;

int p[N], cnt[N], rnk[N];

void init() {
	rep(i, 0, N) {
		p[i] = i;
		cnt[i] = 0;
		rnk[i] = 0;
	}
}

int get(int v) {
	return (p[v] == v ? v : (p[v] = get(p[v])));
}

void unite(int u, int v) {
	u = get(u);
	v = get(v);
	if (u == v) {
		return;
	}
	if (rnk[u] > rnk[v]) {
		swap(u, v);
	} else if (rnk[u] == rnk[v]) {
		rnk[v]++;
	}
	p[u] = v;
	cnt[v] += cnt[u];
}

void run() {
	string s;
	cin >> s;
	int n = sz(s);
	vector<int> pal = manaher(s);
	vector<int> arr = suff_arr(s);
	vector<int> lcp = get_lcp(s, arr);
	vector<int> pos(n);
	rep(i, 0, n) {
		pos[arr[i]] = i;
	}
	
	ll ans = 0;
	
	vector<pair<int, int>> by_lcp(n);
	rep(i, 0, n) {
		by_lcp[i] = {lcp[i], i};
	}
	sort(all(by_lcp));
	reverse(all(by_lcp));
	
	init();
	
	{
		vector<pair<int, int>> pals(n);
		rep(i, 0, n) {
			pals[i] = {pal[2 * i + 1] / 2, i};
		}
		sort(all(pals));
		reverse(all(pals));
		int ptr = 0;
		rep(i, 0, n) {
			int len = pals[i].first;
			while (ptr < n && by_lcp[ptr].first >= len) {
				unite(by_lcp[ptr].second, by_lcp[ptr].second + 1);
				ptr++;
			}
			int v = get(pos[pals[i].second]);
			cnt[v]++;
			maxi(ans, cnt[v] * (2LL * len - 1));
		}
	}
	
	init();
	
	{
		vector<pair<int, int>> pals(n - 1);
		rep(i, 1, n) {
			pals[i - 1] = {pal[2 * i] / 2, i};
		}
		sort(all(pals));
		reverse(all(pals));
		int ptr = 0;
		rep(i, 0, n - 1) {
			int len = pals[i].first;
			if (len == 0) {
				break;
			}
			while (ptr < n && by_lcp[ptr].first >= len) {
				unite(by_lcp[ptr].second, by_lcp[ptr].second + 1);
				ptr++;
			}
			int v = get(pos[pals[i].second]);
			cnt[v]++;
			maxi(ans, cnt[v] * 2LL * len);
		}
	}
	
	cout << ans << "\n";
}

Compilation message

palindrome.cpp: In function 'int main()':
palindrome.cpp:72:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
         freopen(TASK ".in", "r", stdin);
                                        ^
palindrome.cpp:73:42: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
         freopen(TASK ".out", "w", stdout);
                                          ^

Subtask #1
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 5700 KB Output is correct
2 Correct 0 ms 5700 KB Output is correct
3 Correct 0 ms 5700 KB Output is correct
4 Correct 0 ms 5700 KB Output is correct
5 Correct 0 ms 5700 KB Output is correct
6 Correct 0 ms 5700 KB Output is correct
7 Correct 3 ms 5700 KB Output is correct
8 Correct 0 ms 5700 KB Output is correct
9 Correct 3 ms 5700 KB Output is correct
10 Correct 0 ms 5700 KB Output is correct
11 Correct 0 ms 5700 KB Output is correct
12 Correct 0 ms 5700 KB Output is correct
13 Correct 3 ms 5700 KB Output is correct
14 Correct 3 ms 5700 KB Output is correct
15 Correct 3 ms 5700 KB Output is correct
16 Correct 3 ms 5700 KB Output is correct
17 Correct 3 ms 5700 KB Output is correct
18 Correct 3 ms 5700 KB Output is correct
19 Correct 0 ms 5700 KB Output is correct
20 Correct 0 ms 5700 KB Output is correct
21 Correct 3 ms 5700 KB Output is correct
22 Correct 3 ms 5700 KB Output is correct
23 Correct 0 ms 5700 KB Output is correct
24 Correct 3 ms 5700 KB Output is correct
25 Correct 0 ms 5700 KB Output is correct
26 Correct 3 ms 5700 KB Output is correct
27 Correct 3 ms 5700 KB Output is correct
28 Correct 3 ms 5700 KB Output is correct
29 Correct 0 ms 5700 KB Output is correct
30 Correct 3 ms 5700 KB Output is correct
31 Correct 3 ms 5700 KB Output is correct
32 Correct 3 ms 5700 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 5700 KB Output is correct
2 Correct 3 ms 5700 KB Output is correct
3 Correct 3 ms 5700 KB Output is correct
4 Correct 0 ms 5700 KB Output is correct
5 Correct 3 ms 5700 KB Output is correct
6 Correct 0 ms 5700 KB Output is correct
7 Correct 3 ms 5700 KB Output is correct
8 Correct 0 ms 5700 KB Output is correct
9 Correct 0 ms 5700 KB Output is correct
10 Correct 3 ms 5700 KB Output is correct
11 Correct 3 ms 5700 KB Output is correct
12 Correct 3 ms 5700 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 6044 KB Output is correct
2 Correct 6 ms 6044 KB Output is correct
3 Correct 9 ms 6044 KB Output is correct
4 Correct 9 ms 6044 KB Output is correct
5 Correct 9 ms 6044 KB Output is correct
6 Correct 9 ms 6044 KB Output is correct
7 Correct 6 ms 6044 KB Output is correct
8 Correct 9 ms 6044 KB Output is correct
9 Correct 9 ms 6044 KB Output is correct
10 Correct 9 ms 6044 KB Output is correct

Subtask #4
26.0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 79 ms 9700 KB Output is correct
2 Correct 79 ms 9700 KB Output is correct
3 Correct 106 ms 9700 KB Output is correct
4 Correct 76 ms 9700 KB Output is correct
5 Correct 106 ms 9700 KB Output is correct
6 Correct 113 ms 9700 KB Output is correct
7 Correct 119 ms 9700 KB Output is correct
8 Correct 159 ms 9700 KB Output is correct
9 Correct 126 ms 9700 KB Output is correct
10 Correct 113 ms 9700 KB Output is correct

Subtask #5
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 283 ms 17672 KB Output is correct
2 Correct 266 ms 17672 KB Output is correct
3 Correct 319 ms 17672 KB Output is correct
4 Correct 276 ms 17672 KB Output is correct
5 Correct 543 ms 17672 KB Output is correct
6 Correct 426 ms 17672 KB Output is correct
7 Correct 423 ms 17672 KB Output is correct
8 Correct 889 ms 17672 KB Output is correct
9 Correct 799 ms 17672 KB Output is correct
10 Correct 409 ms 17672 KB Output is correct
11 Correct 233 ms 17672 KB Output is correct
12 Correct 773 ms 17672 KB Output is correct