Submission #492977

#	Time	Username	Problem	Language	Result	Execution time	Memory
492977		MilosMilutinovic	Palindromic Partitions (CEOI17_palindromic)	C++14	100 / 100	181 ms	26684 KiB

palindromic

#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(random_device{}()); 
const ll mod=1000000007;
const ll p=6983;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head

const int N=1000005;
int n,_;
char s[N];
ll pw[N],hsh[N];

ll get(int l,int r) {
	ll hash=hsh[r]-(hsh[l]*pw[r-l])%mod;
	if (hash<0) hash+=mod;
	return hash;
}

bool check(int l,int r,int len) {
	return get(l-1,l+len-1)==get(r-len,r);
}

void solve() {
	scanf("%s",s+1);
	n=strlen(s+1);
	hsh[0]=0;
	pw[0]=1;
	rep(i,1,n+1) pw[i]=(pw[i-1]*p)%mod;
	rep(i,1,n+1) {
		hsh[i]=((hsh[i-1]*p)+s[i])%mod;
	}
	int l=1,r=n;
	int ans=0;
	while (l<=r) {
		if (l==r) {
			ans++;
			break;
		}
		if (l+1==r) {
			if (s[l]==s[r]) ans++;
			ans++;
			break;
		}
		int suc=1;
		rep(i,1,n) {
			if (l+i-1>=r-i+1) {
				suc=0;
				break;
			}
			if (check(l,r,i)) {
				ans+=2;
				l+=i,r-=i;
				break;
			}
		}
		if (!suc) {
			ans++;
			break;
		}
	}
	printf("%d\n",ans);
}

int main() {
	for (scanf("%d",&_);_;_--) {
		solve();
	}
}

Compilation message (stderr)

palindromic.cpp: In function 'void solve()':
palindromic.cpp:39:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   39 |  scanf("%s",s+1);
      |  ~~~~~^~~~~~~~~~
palindromic.cpp: In function 'int main()':
palindromic.cpp:80:12: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   80 |  for (scanf("%d",&_);_;_--) {
      |       ~~~~~^~~~~~~~~

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