#include <bits/stdc++.h>
using namespace std;
#define in ({int x=0;int c=getchar(),n=0;for(;!isdigit(c);c=getchar()) n=(c=='-');for(;isdigit(c);c=getchar()) x=x*10+c-'0';n?-x:x;})
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int rnd(int l,int r){return l+rng()%(r-l+1);}
#define fasty ios_base::sync_with_stdio(0),cin.tie(0);
#define forinc(a,b,c) for(int a=b,_c=c;a<=_c;++a)
#define fordec(a,b,c) for(int a=b,_c=c;a>=_c;--a)
#define forv(a,b) for(auto&a:b)
#define fi first
#define se second
#define pb push_back
#define ii pair<int,int>
#define mt make_tuple
#define all(a) a.begin(),a.end()
#define reset(f, x) memset(f, x, sizeof(f))
#define bit(x,i) ((x>>(i-1))&1)
#define on(x,i) (x|(1ll<<(i-1)))
#define off(x,i) (x&~(1<<(i-1)))
#define gg exit(0);
const int N=300010,
M=1000000007;
int n,gap,ret;
int pos[N],sa[N],tmp[N],lcp[N],ln[N];
int f[22][N];
string s;
unsigned long long pw1[N], h1[N], g1[N];
long long pw2[N], h2[N], g2[N];
int cmp(int i,int j){
if(pos[i]!=pos[j]) return pos[i]<pos[j];
i+=gap, j+=gap;
return i<=n && j<=n ? pos[i]<pos[j] : i>j;
}
int que(int i,int j){
int t=ln[j-i+1];
return min(f[t][i],f[t][j-(1<<t)+1]);
}
int palin(int i,int j){
return h1[j]-h1[i-1]*pw1[j-i+1] == g1[i]-g1[j+1]*pw1[j-i+1] &&
(h2[j]-h2[i-1]*pw2[j-i+1]%M+M)%M == (g2[i]-g2[j+1]*pw2[j-i+1]%M+M)%M;
}
main(){
#define task "palindrome"
//freopen(task".inp","r",stdin);
//freopen(task".out","w",stdout);
fasty;
cin>>s; n=s.size(); s=" "+s;
forinc(i,0,n) pw1[i]=i?pw1[i-1]*19937:1, pw2[i]=i?pw2[i-1]*47%M:1;
forinc(i,1,n) sa[i]=i, pos[i]=s[i], ln[i]=log2(i);
forinc(i,1,n) h1[i]=h1[i-1]*19937+s[i], h2[i]=(h2[i-1]*47+s[i])%M;
fordec(i,n,1) g1[i]=g1[i+1]*19937+s[i], g2[i]=(g2[i+1]*47+s[i])%M;
for(gap=1;;gap+=gap){
sort(sa+1,sa+n+1,cmp);
forinc(i,1,n-1) tmp[i+1]=tmp[i]+cmp(sa[i],sa[i+1]);
forinc(i,1,n) pos[sa[i]]=tmp[i]+1;
if(tmp[n]==n-1) break;
}
for(int i=1,k=0;i<=n;++i){
for(int j=sa[pos[i]+1];s[i+k]==s[j+k];) k++;
lcp[pos[i]]=k;
if(k) k--;
}
forinc(i,1,n) f[0][i]=lcp[i];
forinc(j,1,20) forinc(i,1,n){
if(i+1<<j>n+1) continue;
f[j][i]=min(f[j-1][i],f[j-1][i+(1<<j-1)]);
}
forinc(len,1,n){
int le,mi,ri,lf,rt;
//for(int l=1;l+len-1<=n;l+=len){
forinc(l,1,n-len+1){
int r=l+len-1;
if(!palin(l,r)) continue;
lf=rt=pos[l];
le=pos[l],ri=n;
while(le<=ri){
mi=(le+ri)/2;
if(que(pos[l],mi-1)>=len) rt=mi, le=mi+1;
else ri=mi-1;
}
le=1,ri=pos[l];
while(le<=ri){
mi=(le+ri)/2;
if(que(mi,pos[l]-1)>=len) lf=mi, ri=mi-1;
else le=mi+1;
}
ret=max(ret,len*(rt-lf+1));
}
}
cout<<ret;
}
Compilation message
palindrome.cpp:49:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
main(){
^
palindrome.cpp: In function 'int main()':
palindrome.cpp:76:13: warning: suggest parentheses around '+' inside '<<' [-Wparentheses]
if(i+1<<j>n+1) continue;
~^~
palindrome.cpp:77:45: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
f[j][i]=min(f[j-1][i],f[j-1][i+(1<<j-1)]);
~^~
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
4 ms |
256 KB |
Output is correct |
2 |
Correct |
4 ms |
384 KB |
Output is correct |
3 |
Correct |
4 ms |
384 KB |
Output is correct |
4 |
Correct |
4 ms |
384 KB |
Output is correct |
5 |
Correct |
5 ms |
384 KB |
Output is correct |
6 |
Correct |
5 ms |
384 KB |
Output is correct |
7 |
Correct |
4 ms |
384 KB |
Output is correct |
8 |
Correct |
4 ms |
384 KB |
Output is correct |
9 |
Correct |
5 ms |
512 KB |
Output is correct |
10 |
Incorrect |
5 ms |
384 KB |
Output isn't correct |
11 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
24 ms |
512 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Execution timed out |
1094 ms |
1408 KB |
Time limit exceeded |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Execution timed out |
1094 ms |
9460 KB |
Time limit exceeded |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Execution timed out |
1098 ms |
27816 KB |
Time limit exceeded |
2 |
Halted |
0 ms |
0 KB |
- |