답안 #318182

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
318182 2020-10-31T15:20:34 Z Benq Palinilap (COI16_palinilap) C++14
100 / 100
198 ms 37308 KB
#include <bits/stdc++.h>
using namespace std;
 
using ll = long long;
using ld = long double;
using db = double; 
using str = string; // yay python!

using pi = pair<int,int>;
using pl = pair<ll,ll>;
using pd = pair<db,db>;

using vi = vector<int>;
using vb = vector<bool>;
using vl = vector<ll>;
using vd = vector<db>; 
using vs = vector<str>;
using vpi = vector<pi>;
using vpl = vector<pl>; 
using vpd = vector<pd>;

#define tcT template<class T
#define tcTU tcT, class U
// ^ lol this makes everything look weird but I'll try it
tcT> using V = vector<T>; 
tcT, size_t SZ> using AR = array<T,SZ>; 
tcT> using PR = pair<T,T>;

// pairs
#define mp make_pair
#define f first
#define s second

// vectors
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
#define rall(x) (x).rbegin(), (x).rend() 
#define sor(x) sort(all(x)) 
#define rsz resize
#define ins insert 
#define ft front() 
#define bk back()
#define pf push_front 
#define pb push_back
#define eb emplace_back 
#define lb lower_bound 
#define ub upper_bound 

// loops
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)

const int MOD = 1e9+7; // 998244353;
const int MX = 2e5+5;
const ll INF = 1e18; // not too close to LLONG_MAX
const ld PI = acos((ld)-1);
const int dx[4] = {1,0,-1,0}, dy[4] = {0,1,0,-1}; // for every grid problem!!
mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count()); 
template<class T> using pqg = priority_queue<T,vector<T>,greater<T>>;

// helper funcs
constexpr int pct(int x) { return __builtin_popcount(x); } // # of bits set
constexpr int bits(int x) { return 31-__builtin_clz(x); } // floor(log2(x)) 
ll cdiv(ll a, ll b) { return a/b+((a^b)>0&&a%b); } // divide a by b rounded up
ll fdiv(ll a, ll b) { return a/b-((a^b)<0&&a%b); } // divide a by b rounded down

tcT> bool ckmin(T& a, const T& b) {
	return b < a ? a = b, 1 : 0; } // set a = min(a,b)
tcT> bool ckmax(T& a, const T& b) {
	return a < b ? a = b, 1 : 0; }

tcTU> T fstTrue(T lo, T hi, U f) {
	hi ++; assert(lo <= hi); // assuming f is increasing
	while (lo < hi) { // find first index such that f is true 
		T mid = lo+(hi-lo)/2;
		f(mid) ? hi = mid : lo = mid+1; 
	} 
	return lo;
}
tcTU> T lstTrue(T lo, T hi, U f) {
	lo --; assert(lo <= hi); // assuming f is decreasing
	while (lo < hi) { // find first index such that f is true 
		T mid = lo+(hi-lo+1)/2;
		f(mid) ? lo = mid : hi = mid-1;
	} 
	return lo;
}
tcT> void remDup(vector<T>& v) { // sort and remove duplicates
	sort(all(v)); v.erase(unique(all(v)),end(v)); }
tcTU> void erase(T& t, const U& u) { // don't erase
	auto it = t.find(u); assert(it != end(t));
	t.erase(u); } // element that doesn't exist from (multi)set

// INPUT
#define tcTUU tcT, class ...U
tcT> void re(complex<T>& c);
tcTU> void re(pair<T,U>& p);
tcT> void re(vector<T>& v);
tcT, size_t SZ> void re(AR<T,SZ>& a);

tcT> void re(T& x) { cin >> x; }
void re(db& d) { str t; re(t); d = stod(t); }
void re(ld& d) { str t; re(t); d = stold(t); }
tcTUU> void re(T& t, U&... u) { re(t); re(u...); }

tcT> void re(complex<T>& c) { T a,b; re(a,b); c = {a,b}; }
tcTU> void re(pair<T,U>& p) { re(p.f,p.s); }
tcT> void re(vector<T>& x) { trav(a,x) re(a); }
tcT, size_t SZ> void re(AR<T,SZ>& x) { trav(a,x) re(a); }
tcT> void rv(int& n, vector<T>& x) { re(n); x.rsz(n); trav(a,x) re(a); }

// TO_STRING
#define ts to_string
str ts(char c) { return str(1,c); }
str ts(const char* s) { return (str)s; }
str ts(str s) { return s; }
str ts(bool b) { 
	#ifdef LOCAL
		return b ? "true" : "false"; 
	#else 
		return ts((int)b);
	#endif
}
tcT> str ts(complex<T> c) { 
	stringstream ss; ss << c; return ss.str(); }
str ts(vector<bool> v) {
	str res = "{"; F0R(i,sz(v)) res += char('0'+v[i]);
	res += "}"; return res; }
template<size_t SZ> str ts(bitset<SZ> b) {
	str res = ""; F0R(i,SZ) res += char('0'+b[i]);
	return res; }
tcTU> str ts(pair<T,U> p);
tcT> str ts(T v) { // containers with begin(), end()
	#ifdef LOCAL
		bool fst = 1; str res = "{";
		for (const auto& x: v) {
			if (!fst) res += ", ";
			fst = 0; res += ts(x);
		}
		res += "}"; return res;
	#else
		bool fst = 1; str res = "";
		for (const auto& x: v) {
			if (!fst) res += " ";
			fst = 0; res += ts(x);
		}
		return res;

	#endif
}
tcTU> str ts(pair<T,U> p) {
	#ifdef LOCAL
		return "("+ts(p.f)+", "+ts(p.s)+")"; 
	#else
		return ts(p.f)+" "+ts(p.s);
	#endif
}

// OUTPUT
tcT> void pr(T x) { cout << ts(x); }
tcTUU> void pr(const T& t, const U&... u) { 
	pr(t); pr(u...); }
void ps() { pr("\n"); } // print w/ spaces
tcTUU> void ps(const T& t, const U&... u) { 
	pr(t); if (sizeof...(u)) pr(" "); ps(u...); }

// DEBUG
void DBG() { cerr << "]" << endl; }
tcTUU> void DBG(const T& t, const U&... u) {
	cerr << ts(t); if (sizeof...(u)) cerr << ", ";
	DBG(u...); }
#ifdef LOCAL // compile with -DLOCAL, chk -> fake assert
	#define dbg(...) cerr << "Line(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
	#define chk(...) if (!(__VA_ARGS__)) cerr << "Line(" << __LINE__ << ") -> function(" \
		 << __FUNCTION__  << ") -> CHK FAILED: (" << #__VA_ARGS__ << ")" << "\n", exit(0);
#else
	#define dbg(...) 0
	#define chk(...) 0
#endif

// FILE I/O
void setIn(str s) { freopen(s.c_str(),"r",stdin); }
void setOut(str s) { freopen(s.c_str(),"w",stdout); }
void unsyncIO() { cin.tie(0)->sync_with_stdio(0); }
void setIO(str s = "") {
	unsyncIO();
	// cin.exceptions(cin.failbit); 
	// throws exception when do smth illegal
	// ex. try to read letter into int
	if (sz(s)) { setIn(s+".in"), setOut(s+".out"); } // for USACO
}

/**
 * Description: Polynomial hash for substrings with two bases.
 * Source:
	* KACTL
	* https://codeforces.com/contest/1207/submission/59309672
 * Verification: 
	* USACO Dec 17 Plat 1 (LCP :o)
	* CF Check Transcription
 */

typedef array<int,2> H; // bases not too close to ends 
uniform_int_distribution<int> BDIST(0.1*MOD,0.9*MOD);
const H base = {BDIST(rng),BDIST(rng)};
/// const T ibase = {(int)inv(mi(base[0])),(int)inv(mi(base[1]))};
H operator+(H l, H r) { 
	F0R(i,2) if ((l[i] += r[i]) >= MOD) l[i] -= MOD;
	return l; }
H operator-(H l, H r) { 
	F0R(i,2) if ((l[i] -= r[i]) < 0) l[i] += MOD;
	return l; }
H operator*(H l, H r) { 
	F0R(i,2) l[i] = (ll)l[i]*r[i]%MOD;
	return l; }
H makeH(char c) { return {c,c}; }
/// H& operator+=(H& l, H r) { return l = l+r; }
/// H& operator-=(H& l, H r) { return l = l-r; }
/// H& operator*=(H& l, H r) { return l = l*r; }

vector<H> pows = {{1,1}};
struct HashRange {
	str S; vector<H> cum = {{0,0}};
	void add(char c) { S += c; cum.pb(base*cum.bk+makeH(c)); }
	void add(str s) { trav(c,s) add(c); }
	void extend(int len) { while (sz(pows) <= len) pows.pb(base*pows.bk); }
	H hash(int l, int r) { int len = r+1-l; extend(len);
		return cum[r+1]-pows[len]*cum[l]; }
	/**int lcp(HashRange& b) { return first_true([&](int x) { 
		return cum[x] != b.cum[x]; },0,min(sz(S),sz(b.S)))-1; }*/
};
/// HashRange HR; HR.add("ababab"); F0R(i,6) FOR(j,i,6) ps(i,j,HR.hash(i,j));

HashRange hr, hr_rev;
int N;

str W;
map<char,ll> ad[MX];
ll lin[MX], cons[MX];
ll ans;

H hash_nor(int l, int r) { return hr.hash(l,r); }
H hash_rev(int l, int r) { return hr_rev.hash(N-1-r,N-1-l); }

void sub_range(int l, int r) {
	if (l > r) return;
	auto add_linear = [&](int l, int r, int x) { lin[l] += x, lin[r] -= x; };
	auto add_cons = [&](int l, int r, int x) { cons[l] += x, cons[r] -= x; };
	add_linear(l,(l+r+1)/2,1);
	add_cons  (l,(l+r+1)/2,-(l-1));
	add_linear((l+r+2)/2,r+1,-1);
	add_cons  ((l+r+2)/2,r+1,r+1);
	// FOR(i,l,(l+r+1)/2) sub[i] += i-(l-1);
	// FOR(i,(l+r+2)/2,r+1) sub[i] += r+1-i;
	// int cnt = 0;
	// while (l < r) {
	// 	cnt ++;
	// 	sub[l] += cnt, sub[r] += cnt;
	// 	l ++, r --;
	// }
}

void account(int l, int r) {
	int mx = min(l,N-1-r);
	int len = lstTrue(0,mx,[&](int x){
		return hash_nor(l-x,r+x) == hash_rev(l-x,r+x);
	});
	ans += len + (l == r);
	sub_range(l-len,r+len); // l-len to r+len is a palindrome
	if (l-len > 0 && r+len < N-1) {
		int new_len = lstTrue(len+2,mx,[&](int x){
			return hash_nor(l-x,l-len-2) == hash_rev(r+len+2,r+x);
		});
		ad[l-len-1][W[r+len+1]] += new_len-len;
		ad[r+len+1][W[l-len-1]] += new_len-len;
	}
}

int main() {
	setIO(); re(W); N = sz(W);
	hr.add(W); reverse(all(W));
	hr_rev.add(W); reverse(all(W));
	F0R(i,N) account(i,i);
	F0R(i,N-1) account(i+1,i);
	FOR(i,1,N) lin[i] += lin[i-1], cons[i] += cons[i-1];
	ll bes = 0;
	F0R(i,N) trav(t,ad[i]) ckmax(bes,t.s-lin[i]*i-cons[i]);
	ps(bes+ans);
}

/* stuff you should look for
	* int overflow, array bounds
	* special cases (n=1?)
	* do smth instead of nothing and stay organized
	* WRITE STUFF DOWN
	* DON'T GET STUCK ON ONE APPROACH
*/

Compilation message

palinilap.cpp: In function 'void setIn(str)':
palinilap.cpp:185:28: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  185 | void setIn(str s) { freopen(s.c_str(),"r",stdin); }
      |                     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
palinilap.cpp: In function 'void setOut(str)':
palinilap.cpp:186:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  186 | void setOut(str s) { freopen(s.c_str(),"w",stdout); }
      |                      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 9708 KB Output is correct
2 Correct 6 ms 9708 KB Output is correct
3 Correct 6 ms 9708 KB Output is correct
4 Correct 6 ms 9708 KB Output is correct
5 Correct 8 ms 9836 KB Output is correct
# 결과 실행 시간 메모리 Grader output
1 Correct 10 ms 10348 KB Output is correct
2 Correct 11 ms 10348 KB Output is correct
3 Correct 12 ms 10476 KB Output is correct
4 Correct 10 ms 10348 KB Output is correct
5 Correct 13 ms 10508 KB Output is correct
6 Correct 13 ms 10476 KB Output is correct
7 Correct 15 ms 11116 KB Output is correct
# 결과 실행 시간 메모리 Grader output
1 Correct 168 ms 19960 KB Output is correct
2 Correct 129 ms 20328 KB Output is correct
3 Correct 121 ms 20436 KB Output is correct
4 Correct 178 ms 25300 KB Output is correct
5 Correct 177 ms 25432 KB Output is correct
6 Correct 177 ms 25556 KB Output is correct
7 Correct 176 ms 25560 KB Output is correct
8 Correct 86 ms 15192 KB Output is correct
9 Correct 176 ms 25556 KB Output is correct
10 Correct 175 ms 25300 KB Output is correct
11 Correct 116 ms 20312 KB Output is correct
12 Correct 170 ms 20824 KB Output is correct
13 Correct 173 ms 21064 KB Output is correct
14 Correct 180 ms 26712 KB Output is correct
15 Correct 179 ms 25556 KB Output is correct
16 Correct 155 ms 26584 KB Output is correct
17 Correct 196 ms 37204 KB Output is correct
18 Correct 174 ms 20568 KB Output is correct
19 Correct 198 ms 37308 KB Output is correct