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Submission #230795

# Submission time Handle Problem Language Result Execution time Memory
230795 2020-05-11T20:08:15 Z alishahali1382 Palindromes (APIO14_palindrome) C++14
47 / 100
 1000 ms 81144 KB 
#include <bits/stdc++.h>
#pragma GCC optimize ("O2")
#pragma GCC optimize ("unroll-loops")
//#pragma GCC optimize("no-stack-protector,fast-math")

using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<pii, int> piii;
typedef pair<ll, ll> pll;
#define debug(x) cerr<<#x<<'='<<(x)<<endl;
#define debugp(x) cerr<<#x<<"= {"<<(x.first)<<", "<<(x.second)<<"}"<<endl;
#define debug2(x, y) cerr<<"{"<<#x<<", "<<#y<<"} = {"<<(x)<<", "<<(y)<<"}"<<endl;
#define debugv(v) {cerr<<#v<<" : ";for (auto x:v) cerr<<x<<' ';cerr<<endl;}
#define all(x) x.begin(), x.end()
#define pb push_back
#define kill(x) return cout<<x<<'\n', 0;

const ld eps=1e-7;
const int inf=1000000010;
const ll INF=10000000000000010LL;
const int mod=1000000007;
const int MAXN=300010, LOG=21;

int n, m, k, u, v, x, y, t, a, b;
ll ans;
int Rank[MAXN<<1][LOG], P[MAXN<<1], pw;
int lcp[MAXN], L[MAXN], R[MAXN];
vector<int> seg[MAXN<<2];
string S;

inline bool cmp(int x, int y){
	if (Rank[x][pw-1]!=Rank[y][pw-1]) return Rank[x][pw-1]<Rank[y][pw-1];
	if (max(x, y)+(1<<(pw-1))>=m) return x>y;
	return Rank[x+(1<<(pw-1))][pw-1]<Rank[y+(1<<(pw-1))][pw-1];
}

void BuildSuffixArray(){
	for (int i=0; i<m; i++) Rank[i][0]=S[i], P[i]=i;
	for (pw=1; pw<LOG; pw++){
		sort(P, P+m, cmp);
		Rank[P[0]][pw]=0;
		for (int i=1; i<m; i++) Rank[P[i]][pw]=Rank[P[i-1]][pw] + cmp(P[i-1], P[i]);
	}
}

int GetLcp(int x, int y){
	if (x>y) swap(x, y);
	int res=0;
	for (int i=LOG-1; ~i; i--) if (y<m && Rank[x][i]==Rank[y][i]){
		x+=(1<<i);
		y+=(1<<i);
		res|=(1<<i);
	}
	return res;
}

void Add(int id, int tl, int tr, int l, int r, int val){
	//if (id==1) cerr<<"Add "<<l<<' '<<r<<' '<<val<<endl;
	if (r<=tl || tr<=l) return ;
	if (l<=tl && tr<=r){
		seg[id].pb(val);
		return ;
	}
	int mid=(tl+tr)>>1;
	Add(id<<1, tl, mid, l, r, val);
	Add(id<<1 | 1, mid, tr, l, r, val);
}

int GetPalindrome(int id, int tl, int tr, int pos, int val){
	if (pos<tl || tr<=pos) return 0;
	int res=0;
	if (seg[id].size() && seg[id][0]<val) res=(*--lower_bound(all(seg[id]), val))-2*pos+1;
	if (tr-tl==1) return res;
	int mid=(tl+tr)>>1;
	return max(res, max(GetPalindrome(id<<1, tl, mid, pos, val), GetPalindrome(id<<1 | 1, mid, tr, pos, val)));
}

int main(){
	ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);
	cin>>S;
	n=S.size();
	S+="#";
	for (int i=n-1; ~i; i--) S+=S[i];
	m=S.size();
	BuildSuffixArray();
	/*
	debug(S)
	debug(GetLcp(0, 2*n))
	for (int i=0; i<m; i++) cerr<<P[i]<<" \n"[i==m-1];
	*/
	
	for (int i=0; i<n; i++){
		int len=GetLcp(i+1, 2*n-i);
		Add(1, 0, n, i+1-len, i+1, 2*i+1);
		ans=max(ans, 2ll*len);
	}
	for (int i=0; i<n; i++){
		int len=GetLcp(i, 2*n-i);
		Add(1, 0, n, i-len+1, i+1, 2*i);
		ans=max(ans, 2*len-1ll);
	}
	for (int i=0; i<4*MAXN; i++) sort(all(seg[i]));
	for (int i=0; i+1<m; i++) lcp[i]=GetLcp(P[i], P[i+1]);
	for (int i=0; i+1<m; i++) for (L[i]=i-1; ~L[i] && lcp[L[i]]>=lcp[i]; L[i]=L[L[i]]);
	for (int i=m-2; i; i--) for (R[i]=i+1; R[i]<m-1 && lcp[R[i]]>=lcp[i]; R[i]=R[R[i]]);
	for (int i=0; i<=m-2; i++){
		ll ted=(R[i]-L[i])/2;
		ans=max(ans, GetPalindrome(1, 0, n, P[i], 2*P[i]+lcp[i])*ted);
		//debug2(P[i], GetPalindrome(1, 0, n, P[i], 2*P[i]+lcp[i]))
	}
	cout<<ans<<'\n';
	
	return 0;
}

Subtask #1
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 23 ms 28544 KB Output is correct
2 Correct 23 ms 28544 KB Output is correct
3 Correct 23 ms 28544 KB Output is correct
4 Correct 23 ms 28544 KB Output is correct
5 Correct 23 ms 28544 KB Output is correct
6 Correct 24 ms 28544 KB Output is correct
7 Correct 23 ms 28544 KB Output is correct
8 Correct 23 ms 28544 KB Output is correct
9 Correct 23 ms 28544 KB Output is correct
10 Correct 25 ms 28544 KB Output is correct
11 Correct 23 ms 28544 KB Output is correct
12 Correct 23 ms 28544 KB Output is correct
13 Correct 23 ms 28544 KB Output is correct
14 Correct 23 ms 28612 KB Output is correct
15 Correct 24 ms 28544 KB Output is correct
16 Correct 24 ms 28672 KB Output is correct
17 Correct 24 ms 28544 KB Output is correct
18 Correct 23 ms 28544 KB Output is correct
19 Correct 24 ms 28544 KB Output is correct
20 Correct 23 ms 28544 KB Output is correct
21 Correct 24 ms 28544 KB Output is correct
22 Correct 23 ms 28544 KB Output is correct
23 Correct 23 ms 28544 KB Output is correct
24 Correct 23 ms 28544 KB Output is correct
25 Correct 23 ms 28544 KB Output is correct
26 Correct 23 ms 28544 KB Output is correct
27 Correct 23 ms 28612 KB Output is correct
28 Correct 24 ms 28544 KB Output is correct
29 Correct 23 ms 28544 KB Output is correct
30 Correct 23 ms 28544 KB Output is correct
31 Correct 23 ms 28544 KB Output is correct
32 Correct 23 ms 28544 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 26 ms 28800 KB Output is correct
2 Correct 26 ms 28836 KB Output is correct
3 Correct 28 ms 28792 KB Output is correct
4 Correct 26 ms 28800 KB Output is correct
5 Correct 28 ms 28800 KB Output is correct
6 Correct 26 ms 28800 KB Output is correct
7 Correct 27 ms 28800 KB Output is correct
8 Correct 25 ms 28800 KB Output is correct
9 Correct 26 ms 28800 KB Output is correct
10 Correct 25 ms 28800 KB Output is correct
11 Correct 26 ms 28800 KB Output is correct
12 Correct 26 ms 28920 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 66 ms 31480 KB Output is correct
2 Correct 64 ms 31480 KB Output is correct
3 Correct 69 ms 31992 KB Output is correct
4 Correct 72 ms 31992 KB Output is correct
5 Correct 63 ms 30968 KB Output is correct
6 Correct 63 ms 31100 KB Output is correct
7 Correct 62 ms 31352 KB Output is correct
8 Correct 64 ms 30840 KB Output is correct
9 Correct 62 ms 30844 KB Output is correct
10 Correct 63 ms 30968 KB Output is correct

Subtask #4
0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 897 ms 57728 KB Output is correct
2 Correct 792 ms 58240 KB Output is correct
3 Correct 862 ms 63356 KB Output is correct
4 Correct 805 ms 63972 KB Output is correct
5 Execution timed out 1050 ms 52352 KB Time limit exceeded
6 Halted 0 ms 0 KB -

Subtask #5
0 / 27.0

# Verdict Execution time Memory Grader output
1 Execution timed out 1096 ms 81144 KB Time limit exceeded
2 Halted 0 ms 0 KB -