Submission #1248074

#	Time	Username	Problem	Language	Result	Execution time	Memory
1248074		nhnguyen14	Palindromic Partitions (CEOI17_palindromic)	C++20	35 / 100	110 ms	196608 KiB

palindromic

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

template<class X,class Y>
	bool minimize(X &x,Y y){
		if (x>y) return x=y,true; return false;
	}
template<class X,class Y>
	bool maximize(X &x,Y y){
		if (x<y) return x=y,true; return false;
	}

const int N=(int)1e4;
const int inf = (int)1e9+7;
	int dp[N+2][N+2];
	int n;
	
	void reset(int _length){
		for(int i=0;i<=_length+1;++i){
			for(int j=0;j<=_length+1;++j) dp[i][j] = -inf;
		}
		return ; 
	}
	
int p[N+2]={} , h[N+2]= {};
const int base = 256;
const int MOD = 1e9+9;
	string s;
	
	int Get(int l,int r){
		return ((LL)h[r] - (LL)p[r-l+1] * h[l - 1] + (LL)MOD*MOD) % MOD;
	}
	
void solve(){
	cin>>s; s = '#' + s;
	n = s.size()  - 1;
	reset(n);
	p[0] = 1;
	for(int i=1;i<=n;++i) {
		p[i] = (LL)p[i-1]*base % MOD;
		h[i] = ((LL)h[i-1]*base+s[i]) % MOD;
	}

	dp[0][n+1]=0;
	for(int start = 1; start <= n; ++start){
		for(int finish = start;finish<=n;++finish){
			int match_finish = n - start + 1 , match_start = n - finish + 1;		
			if (match_start <= finish) continue;
			if (Get(start,finish)!=Get(match_start,match_finish)) continue;
//			cerr<<start<<' '<<finish<<' '<<match_start << ' '<<match_finish<<'\n';
			maximize(dp[finish][match_start] , dp[start - 1][match_finish+1] + 2);
		}	
	}
	int ans = 0;
	for(int start = 1;start<=n;++start){
		for(int finish = start; finish<=n;++finish){
			maximize(ans , dp[start - 1][finish + 1] + 1);
			maximize(ans , dp[start][finish]);
		}
	}
	cout<<ans<<'\n';
	return ;
}

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0) ; cout.tie(0) ;
	#define name "main"
		if (fopen(name".inp","r")){
			freopen(name".inp","r",stdin);
			freopen(name".out","w",stdout);
		}
		
		int test; cin>>test;
		while(test--) solve();
		
		
	return 0;
}

Compilation message (stderr)

palindromic.cpp: In function 'int main()':
palindromic.cpp:71:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   71 |                         freopen(name".inp","r",stdin);
      |                         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
palindromic.cpp:72:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   72 |                         freopen(name".out","w",stdout);
      |                         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 20 / 20
• Subtask 3: 0 / 25
• Subtask 4: 0 / 40