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답안 #939274

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
939274 2024-03-06T08:01:54 Z vjudge1 Palindromic Partitions (CEOI17_palindromic) C++17
100 / 100
 126 ms 42488 KB 
#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx,avx2,fma")
#include <bits/stdc++.h>
 
#define ff first
#define ss second
#define pb push_back
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define int long long
#define rnd(l, r) uniform_int_distribution<int>(l, r)(rng)
 
using namespace std;

void fp(string name){freopen((name+".in").c_str(),"r",stdin); freopen((name+".out").c_str(),"w",stdout);} 
int pow(int a,int b,int m){int ans=1;while(b){if(b&1){ans=(ans*a)%m;}b>>=1;a=(a*a)%m;}return ans;}
int binpow(int a,int b){int ans=1;while(b){if(b&1){ans=(ans*a);}b>>=1;a=(a*a);}return ans;}
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int mod = 1e8 + 7, N = 1e6 + 100, inf = 1e9, mod2 = 1e9 + 7;

int pw[N], hsh[N], hsh2[N], pw2[N];

int get(int l, int r){
  return (((hsh[r]-hsh[l-1]+mod)%mod)*pw[N - r])%mod; 
}

int get2(int l, int r){
	return (((hsh2[r]-hsh2[l-1]+mod2)%mod2)*pw2[N - r])%mod2;
}

void solve(){
	string s;
	cin >> s;
	int n = s.size();
	s = ' ' + s;
	
	for(int i= 1; i <= n;i++){
		hsh[i]=(hsh[i-1]+((s[i]-'a'+1)*pw[i-1])%mod)%mod;
		hsh2[i]=(hsh2[i-1]+((s[i]-'a'+1)*pw2[i-1])%mod2)%mod2;
	}
	
	vector <int> dp(n + 1, -inf);
	
	dp[0] = 0;
	int ans = 1;
	int mid = n / 2;
	int prev = 1;
	for(int i = 1; i <= mid; i++){
			if(get(n - i + 1, n - prev + 1) == get(prev, i)){
				dp[i] = max(dp[prev - 1] + 2, dp[i]);
				ans = max(dp[i], ans);
				prev = i + 1;
		}
	}
	
	for(int i = 0; i <= (n - 1) / 2; i++){
		ans = max(dp[i] + 1, ans);
	}
	
	cout << ans << endl;
}
 
main(){
	iostream::sync_with_stdio(false);	
    cin.tie(nullptr);
    cout.tie(nullptr);
    pw[0]=1;
    pw2[0] = 1;
	for(int i=1;i<N;i++){
		pw[i]=(pw[i-1]*27)%mod;
		pw2[i] = (pw2[i - 1] * 31) % mod2;
	}
	int t;
	cin >> t;
	while(t--)
		solve();
}	
/*
 * Before implementing the problem:
	
	Do I understand the problem correctly?
	Which places are tricky? What do I need to remember to implement them correctly?
	Which place is the heaviest by implementation? Can I do it simpler?
	Which place is the slowest? Where do I need to be careful about constant factors and where I can choose slower but simpler implementation?
	----------------------------------
	If not AC:
 
	Did you remember to do everything to handle the tricky places you thought about before?
	Is the solution correct?
	Do I understand the problem correctly?
	----------------------------------
	If you have a test on which the solution gives wrong answer:
 
	Is the solution doing what it was supposed to do?
	Is the problem in the code or in the idea?
*/

Compilation message

palindromic.cpp:64:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   64 | main(){
      | ^~~~
palindromic.cpp: In function 'void fp(std::string)':
palindromic.cpp:15:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   15 | void fp(string name){freopen((name+".in").c_str(),"r",stdin); freopen((name+".out").c_str(),"w",stdout);}
      |                      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
palindromic.cpp:15:70: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   15 | void fp(string name){freopen((name+".in").c_str(),"r",stdin); freopen((name+".out").c_str(),"w",stdout);}
      |                                                               ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
15.0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 17244 KB Output is correct
2 Correct 7 ms 17244 KB Output is correct
3 Correct 8 ms 17244 KB Output is correct
4 Correct 7 ms 17296 KB Output is correct
5 Correct 8 ms 17244 KB Output is correct

Subtask #2
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 17244 KB Output is correct
2 Correct 7 ms 17244 KB Output is correct
3 Correct 8 ms 17244 KB Output is correct
4 Correct 7 ms 17296 KB Output is correct
5 Correct 8 ms 17244 KB Output is correct
6 Correct 8 ms 17244 KB Output is correct
7 Correct 7 ms 17244 KB Output is correct
8 Correct 8 ms 17244 KB Output is correct
9 Correct 7 ms 17240 KB Output is correct

Subtask #3
25.0 / 25.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 17244 KB Output is correct
2 Correct 7 ms 17244 KB Output is correct
3 Correct 8 ms 17244 KB Output is correct
4 Correct 7 ms 17296 KB Output is correct
5 Correct 8 ms 17244 KB Output is correct
6 Correct 8 ms 17244 KB Output is correct
7 Correct 7 ms 17244 KB Output is correct
8 Correct 8 ms 17244 KB Output is correct
9 Correct 7 ms 17240 KB Output is correct
10 Correct 8 ms 17500 KB Output is correct
11 Correct 8 ms 17572 KB Output is correct
12 Correct 8 ms 17500 KB Output is correct
13 Correct 8 ms 17500 KB Output is correct

Subtask #4
40.0 / 40.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 17244 KB Output is correct
2 Correct 7 ms 17244 KB Output is correct
3 Correct 8 ms 17244 KB Output is correct
4 Correct 7 ms 17296 KB Output is correct
5 Correct 8 ms 17244 KB Output is correct
6 Correct 8 ms 17244 KB Output is correct
7 Correct 7 ms 17244 KB Output is correct
8 Correct 8 ms 17244 KB Output is correct
9 Correct 7 ms 17240 KB Output is correct
10 Correct 8 ms 17500 KB Output is correct
11 Correct 8 ms 17572 KB Output is correct
12 Correct 8 ms 17500 KB Output is correct
13 Correct 8 ms 17500 KB Output is correct
14 Correct 126 ms 42440 KB Output is correct
15 Correct 77 ms 42376 KB Output is correct
16 Correct 119 ms 42488 KB Output is correct
17 Correct 68 ms 31216 KB Output is correct