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Submission #895229

# Submission time Handle Problem Language Result Execution time Memory
895229 2023-12-29T16:05:51 Z vjudge1 Palinilap (COI16_palinilap) C++17
100 / 100
 236 ms 41192 KB 
#include <bits/stdc++.h>
#define pb push_back
#define pf push_front
using namespace std;
#define F first
#define S second
typedef long long ll;
#define pii pair <int, int>
#define pll pair <ll, ll>
typedef long double ld;
const ll N = 2 * 1e5 + 10, M = 26 + 10;
const ll mod = 1e9 + 7;

ll um(ll a, ll b){
	return ((1LL * a * b) % mod + mod) % mod;
}
ll subr(ll a, ll b){
	return ((1LL * a - b) % mod + mod) % mod;
}
ll add(ll a, ll b){
	return ((1LL * a + b) % mod + mod) % mod;
}
ll p = 293, pr[N];
ll arr[N][M], x[N], hs1[N], hs2[N], n;
ll get(ll l1, ll r1, ll l2, ll r2){
	ll s1 = hs1[r1], s2 = subr(hs2[r2], hs2[l2 + 1]);
	if(l1 != 0) s1 = subr(s1, hs1[l1 - 1]);
	if(l1 >= n - l2 - 1) s2 = um(s2, pr[l1 - (n - l2 - 1)]);
	else s1 = um(s1, pr[n - l2 - 1 - l1]);
	
	if(s1 == s2) return true;
	return false;
}
ll in[N], out[N], incnt[N], outcnt[N];
ll getr(ll from, ll to){
	ll l = 0, r = min(n - to, from + 1);
	while(r - l > 1){
		ll mid = (r + l) / 2;
		if(get(to, to + mid, from, from - mid)) l = mid;
		else r = mid;
	}
	if(x[from] != x[to]) r = 0;
	return r;
}
void calc(ll from, ll to){
	ll r = getr(from, to);
	if(from - r >= 0 && to + r < n){
		from = from - r - 1;
		to = to + r + 1;
		if(from < 0 || to >= n){
			from++;
			to--;
			arr[from][x[to]]++;
			arr[to][x[from]]++;
			return;
		}
		ll lx = 0, rx = min(from + 1, n - to), cm = 1;
		while(rx - lx > 1){
			ll mid = (rx + lx) / 2;
			if(get(to, to + mid, from, from - mid)) lx = mid;
			else rx = mid;
		}
		if(get(to, to + lx, from, from - lx) == true) cm = lx + 2;
		from++;
		to--;
		arr[from][x[to]] += cm;
		arr[to][x[from]] += cm;
	}
}
int main() {
	ios::sync_with_stdio(false);
  	cin.tie(NULL);
  	string s;
  	cin >> s;
  	n = (ll)s.size();
  	// build
  	pr[0] = 1LL;
  	for(ll i = 1; i <= n; i++){
  		pr[i] = um(pr[i - 1], p);
  	}
	for(ll i = 0; i < n; i++){
		x[i] = s[i] - 'a';
		if(i == 0) hs1[i] = x[i];
		else hs1[i] = add(hs1[i - 1], um(x[i], pr[i]));
	}
	for(ll i = n - 1; i >= 0; i--){
		hs2[i] = add(hs2[i + 1], um(x[i], pr[n - i - 1]));
	}
	
	// take answer
  	for(ll i = 0; i < n; i++){
  		ll r = getr(i, i);
  		in[i] += r;
  		incnt[i]++;
  		incnt[i + r]--;
  		
  		arr[i][x[i]] -= r;
  		
  		out[i] += r;
  		outcnt[i]++;
  		if(i - r >= 0) outcnt[i - r]--;
  		
  		r = getr(i, i + 1);
  		if(r == 0 || x[i] != x[i + 1]) continue;
  		in[i + 1] += r;
  		incnt[i + 1]++;
  		incnt[i + 1 + r]--;
  		
  		out[i] += r;
  		outcnt[i]++;
  		if(i - r >= 0) outcnt[i - r]--;
  	}
  	ll cur = 0, c = 0, ans = 0;
  	for(ll i = 0; i < n; i++){
  		cur += in[i];
  		c += incnt[i];
  		arr[i][x[i]] += cur;
  		cur -= c;
  	}
  	cur = c = 0;
  	for(ll i = n - 1; i >= 0; i--){
  		cur += out[i];
  		c += outcnt[i];
  		arr[i][x[i]] += cur;
  		cur -= c;
  		
  		ans += arr[i][x[i]];
  	}
  	// for(ll i = 0; i < n; i++){
  		// cout << arr[i][x[i]] << " ";
  	// }
  	// cout << endl;
  	cur = ans;
  	for(ll i = 0; i < n; i++){
  		calc(i, i);
  		calc(i, i + 1);
  	}
  	ll f1 = -1, f2 = -1;
  	for(ll i = 0; i < n; i++){
  		for(ll j = 0; j < 26; j++){
  			if(j == x[i]) continue;
  			if(cur + arr[i][j] - arr[i][x[i]] + 1 >= ans){
  				ans = max(ans, cur + arr[i][j] - arr[i][x[i]] + 1);
  				f1 = i;
  				f2 = j;
  			}
  		}
  	}
  	if(f1 != -1) x[f1] = f2;
  	for(ll i = 0; i < n; i++){
		if(i == 0) hs1[i] = x[i];
		else hs1[i] = add(hs1[i - 1], um(x[i], pr[i]));
	}
	for(ll i = n - 1; i >= 0; i--){
		hs2[i] = add(hs2[i + 1], um(x[i], pr[n - i - 1]));
	}
  	ll real = 0;
  	for(ll i = 0; i < n; i++){
  		real += getr(i, i);
  		real += getr(i, i + 1);
  	}
  	cout << real;
  return 0;
}

Subtask #1
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 12632 KB Output is correct
2 Correct 2 ms 12636 KB Output is correct
3 Correct 2 ms 12636 KB Output is correct
4 Correct 2 ms 12636 KB Output is correct
5 Correct 1 ms 12636 KB Output is correct

Subtask #2
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 12636 KB Output is correct
2 Correct 8 ms 12800 KB Output is correct
3 Correct 9 ms 12872 KB Output is correct
4 Correct 6 ms 12636 KB Output is correct
5 Correct 8 ms 12812 KB Output is correct
6 Correct 9 ms 12636 KB Output is correct
7 Correct 9 ms 12868 KB Output is correct

Subtask #3
46.0 / 46.0

# Verdict Execution time Memory Grader output
1 Correct 235 ms 40952 KB Output is correct
2 Correct 192 ms 40952 KB Output is correct
3 Correct 196 ms 40848 KB Output is correct
4 Correct 230 ms 40952 KB Output is correct
5 Correct 236 ms 40780 KB Output is correct
6 Correct 225 ms 40948 KB Output is correct
7 Correct 231 ms 40992 KB Output is correct
8 Correct 178 ms 41044 KB Output is correct
9 Correct 225 ms 41044 KB Output is correct
10 Correct 229 ms 40868 KB Output is correct
11 Correct 192 ms 41044 KB Output is correct
12 Correct 231 ms 41192 KB Output is correct
13 Correct 235 ms 41040 KB Output is correct
14 Correct 236 ms 40924 KB Output is correct
15 Correct 232 ms 41076 KB Output is correct
16 Correct 208 ms 41056 KB Output is correct
17 Correct 228 ms 41044 KB Output is correct
18 Correct 235 ms 41048 KB Output is correct
19 Correct 232 ms 40972 KB Output is correct