제출 #39340

#제출 시각아이디문제언어결과실행 시간메모리
39340qoo2p5회문 (APIO14_palindrome)C++14
73 / 100
1000 ms16500 KiB
#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]; void init() { rep(i, 0, N) { p[i] = i; cnt[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; } 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"; }

컴파일 시 표준 에러 (stderr) 메시지

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);
                                          ^
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