Submission #970623

#	Time	Username	Problem	Language	Result	Execution time	Memory
970623		jcelin	Palinilap (COI16_palinilap)	C++14	0 / 100	133 ms	49864 KiB

palinilap

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;

typedef pair<int,int> ii;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<ll> vll;
typedef vector<pll> vpll;

#define PB push_back
#define PF push_front
#define PPB pop_back
#define PPF pop_front
#define X first
#define Y second
#define MP make_pair
#define all(x) (x).begin(), (x).end()

const int mod = 998244353;
const int inf = 1e9 + 7;
const ll INF = 1e18 + 7;
const int logo = 20;
const int MAXN = 1e5 + 7;
const int off = 1 << logo;
const int trsz = off << 1;
const int dx[] = {1, -1, 0, 0};
const int dy[] = {0, 0, -1, 1};
const int base = 31;


string s;
int pw[MAXN], n;
ll ans, delt[MAXN][26];

//1 2 3 ... k
struct tournament{
	ll p[trsz], seg[trsz];
	int ad;
	
	void prop(int x, int lo, int hi){
		if(p[x] == 0) return;
		ll num = (hi - lo);
		seg[x] += p[x] * num;
		seg[x] += num * (num - 1) / (ll)2;
		if(x < off){
			int mid = (lo + hi) / 2;
			p[x * 2] += p[x];
			p[x] += (mid - lo);
			p[x * 2 + 1] += p[x];
		}
		p[x] = 0;
	}
	
	void update(int x, int lo, int hi, int a, int b){
		prop(x, lo, hi);
		if(lo >= b or hi <= a) return;
		if(lo >= a and hi <= b){
			p[x] = ad;
			ad += (hi - lo);
			prop(x, lo, hi);
			return;
		}
		int mid = (lo + hi) / 2;
		update(x * 2, lo, mid, a, b);
		update(x * 2 + 1, mid, hi, a, b);
		seg[x] = seg[x * 2] + seg[x * 2 + 1];
	}
	
	
	void upd(int l, int r){
		ad = 1;
		update(1, 0, off, l, r);
	}
	
	ll query(int x, int lo, int hi, int a, int b){
		prop(x, lo, hi);
		if(lo >= b or hi <= a) return 0;
		if(lo >= a and hi <= b) return seg[x];
		int mid = (lo + hi) / 2;
		return query(x * 2, lo, mid, a, b) + query(x * 2 + 1, mid, hi, a, b);
	}
}t1;


//k k-1 k-2 .. 1
struct tournament2{
	ll p[trsz], seg[trsz];
	int ad;
	
	void prop(int x, int lo, int hi){
		if(p[x] == 0) return;
		ll num = (hi - lo);
		seg[x] += p[x] * num;
		seg[x] += num * (num - 1) / (ll)2;
		if(x < off){
			int mid = (lo + hi) / 2;
			p[x * 2 + 1] += p[x];
			p[x] += (mid - lo);
			p[x * 2] += p[x];
		}
		p[x] = 0;
	}
	
	void update(int x, int lo, int hi, int a, int b){
		prop(x, lo, hi);
		if(lo >= b or hi <= a) return;
		if(lo >= a and hi <= b){
			p[x] = ad;
			ad += (hi - lo);
			prop(x, lo, hi);
			return;
		}
		int mid = (lo + hi) / 2;
		update(x * 2 + 1, mid, hi, a, b);
		update(x * 2, lo, mid, a, b);
		seg[x] = seg[x * 2] + seg[x * 2 + 1];
	}
	
	
	void upd(int l, int r){
		ad = 1;
		update(1, 0, off, l, r);
	}
	
	ll query(int x, int lo, int hi, int a, int b){
		prop(x, lo, hi);
		if(lo >= b or hi <= a) return 0;
		if(lo >= a and hi <= b) return seg[x];
		int mid = (lo + hi) / 2;
		return query(x * 2, lo, mid, a, b) + query(x * 2 + 1, mid, hi, a, b);
	}
}t2;

int add(int a, int b){
	a += b;
	if(a >= mod) a -= mod;
	return a;
}

int sub(int a, int b){
	a -= b;
	if(a < 0) a += mod;
	return a;
}

int mul(ll a, ll b){
	return (a * b) % mod;
}

struct hash{
	vi pf;
	void init(string ss){
		pf.clear();
		pf.PB(0);
		for(int i=1; i<=(int)ss.size(); i++) pf.PB(add(pf.back(), mul(pw[i], ss[i - 1] - 'a')));
	}
	
	int gval(int l, int r){
		return mul(pw[MAXN - 1 - l], sub(pf[r], pf[l - 1]));
	}
}h1, h2;

int vl(int l, int r, bool rev){
	if(rev){
		swap(l, r);
		l = n + 1 - l;
		r = n + 1 - r;
		return h2.gval(l, r);
	}
	
	return h1.gval(l, r);
}


int palin(int l, int r){
	return vl(l, r, 0) == vl(l, r, 1);	
}

void neparni(){
	for(int i=1; i<=n; i++){
		int lo = 1, hi = n, ret = 0;
		while(lo <= hi){
			int mid = (lo + hi) / 2;
			if(i - mid < 1 or i + mid > n){
				hi = mid - 1;
				continue;
			}
			
			if(palin(i - mid, i + mid)) lo = mid + 1, ret = mid;
			else hi = mid - 1;
		}
		
		ans += ret + 1;
		int l1 = i - ret - 1, r1 = i + ret + 1;
		t1.upd(l1 + 1, i);
		t2.upd(i + 1, r1);
		
		if(l1 == 0 or r1 == n + 1) continue;
		//l2 r2
		lo = 1, hi = n, ret = 0;
		while(lo <= hi){
			int mid = (lo + hi) / 2;
			if(l1 - mid < 1 or r1 + mid > n){
				hi = mid - 1;
				continue;
			}
			if(vl(l1 - mid, l1 - 1, 0) == vl(r1 + 1, r1 + mid, 1)) lo = mid + 1, ret = mid;
			else hi = mid - 1;
		}
		
		delt[l1][s[r1 - 1] - 'a'] += ret + 1;
		delt[r1][s[l1 - 1] - 'a'] += ret + 1;	
	}
}

void parni(){
	for(int i=1; i<n; i++){
		int l1, r1, lo, hi, ret;
		if(s[i - 1] != s[i]){
			l1 = i;
			r1 = i + 1;
		}else{
			lo = 1, hi = n, ret = 0;
			while(lo <= hi){
				int mid = (lo + hi) / 2;
				if(i - mid < 1 or i + 1 + mid > n){
					hi = mid - 1;
					continue;
				}
				
				if(palin(i - mid, i + 1 + mid)) lo = mid + 1, ret = mid;
				else hi = mid - 1;
			}
			
			ans += ret + 1;
			l1 = i - ret - 1, r1 = i + 1 + ret + 1;
			t1.upd(l1 + 1, i + 1);
			t2.upd(i + 1, r1);
		}
		if(l1 == 0 or r1 == n + 1) continue;
		
		
		lo = 1, hi = n, ret = 0;
		while(lo <= hi){
			int mid = (lo + hi) / 2;
			if(l1 - mid < 1 or r1 + mid > n){
				hi = mid - 1;
				continue;
			}
			if(vl(l1 - mid, l1 - 1, 0) == vl(r1 + 1, r1 + mid, 1)) lo = mid + 1, ret = mid;
			else hi = mid - 1;
		}
		
		delt[l1][s[r1 - 1] - 'a'] += ret + 1;
		delt[r1][s[l1 - 1] - 'a'] += ret + 1;
	}
}

void solve(){
	pw[0] = 1;
	for(int i=1; i<MAXN; i++) pw[i] = mul(pw[i - 1], base);
	cin >> s;
	n = s.size();
	
	h1.init(s);
	reverse(all(s));
	h2.init(s);
	reverse(all(s));
	
	neparni();
	parni();

	ll cans = ans;
	for(int i=1; i<=n; i++){
		for(int let=0; let<26; let++) cans = max(cans, delt[i][let] + ans);
	}
	cout << cans << "\n";
}

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	int tt = 1;
	//cin >> tt;
	while(tt--) solve();
	return 0;
}

• Subtask 1: 0 / 17
• Subtask 2: 0 / 37
• Subtask 3: 0 / 46