Submission #1013426

#	Time	Username	Problem	Language	Result	Execution time	Memory
1013426		ByeWorld	Palindromic Partitions (CEOI17_palindromic)	C++14	100 / 100	1032 ms	27072 KiB

palindromic

#include <bits/stdc++.h>
// #pragma GCC optimize("O3", "unroll-loops")
#define ll long long
#define int long long
#define pb push_back
#define fi first
#define se second
#define lf (id<<1)
#define rg ((id<<1)|1)
#define md ((l+r)>>1)
#define ld long double
using namespace std;
typedef pair<int,int> pii;
typedef pair<pii, int> ipii;
const int MAXN = 1e6+20;
const int MAXA = 9e3+20;
const ll INF = 1e18+10;
const int LOG = 19;
const int SQRT = 450;
const vector<int> NOL = {};
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const vector<int> dx = {1, -1, 0, 0};
const vector<int> dy = {0, 0, 1, -1};
vector <int> key = {29, 31};
vector <int> mod = {998244353, 1000000007};

int sum(int a, int b, int MOD){ return (a+b)%MOD; }
int mul(int a, int b, int MOD){ return (a*b)%MOD; }
int sub(int a, int b, int MOD){ return (a+MOD-b)%MOD; }
int expo(int a, int b, int MOD){
	if(b==0) return 1;
	int te = expo(a, b/2, MOD); te = mul(te, te, MOD);
	return (b%2 ? mul(te,a,MOD) : te);
}
void chsum(int &a, int b, int MOD){ a = (a+b)%MOD; }
void chmul(int a, int b, int MOD){ a = (a*b)%MOD; }
void chsub(int a, int b, int MOD){ a = (a+MOD-b)%MOD; }

pii pr[MAXN];
pii GET(int x, int y){
	int len = y-x+1;
	pii te = pii(mul(pr[x-1].fi, expo(key[0], len, mod[0]), mod[0]), 
		mul(pr[x-1].se, expo(key[1], len, mod[1]), mod[1]));
	// cout << x <<' ' << y<< " x\n";
	// cout << te.fi << ' ' << te.se << " tee\n";
	pii ret = pii(sub(pr[y].fi, te.fi, mod[0]), sub(pr[y].se, te.se, mod[1]));
	return ret;
}
signed main(){
	// ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	int T; cin >> T;
	while(T--){
		string s; cin >> s; s = '.'+s;
		int n = s.size()-1;
		for(int i=1; i<=n; i++){
			pr[i].fi = sum(mul(pr[i-1].fi, key[0], mod[0]), (int)(s[i]-'a'+1), mod[0]);
			pr[i].se = sum(mul(pr[i-1].se, key[1], mod[1]), (int)(s[i]-'a'+1), mod[1]);
			// cout << i << ' ' << pr[i].fi << ' ' << pr[i].se << " te\n";
		}

		int l=1, r=n, ANS = 0;
		pii le = GET(1, 1), ri = GET(n, n);
		// cout << (GET(2,3)==GET(7,8)) << " pp\n";
		int lasl = 1, lasr = n;
		while(l<r){
			if(le != ri){
				l++; le = GET(lasl, l);
				r--; ri = GET(r, lasr);
			} else {
				// cout << le << ' ' << ri << " pp\n";
				ANS+=2;
				l++; r--;
				lasl = l; lasr = r;
				le = GET(l, l); 
				ri = GET(r, r);
			}
		}
		if(lasl != n/2+1 || lasr != n/2) ANS++;
 		cout << ANS << '\n';
	}
}

• Subtask 1: 15 / 15
• Subtask 2: 20 / 20
• Subtask 3: 25 / 25
• Subtask 4: 40 / 40