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#include <map>
#include <set>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <vector>
#include <cstdio>
#include <string>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
#define X first
#define Y second
#define pb push_back
#define mp make_pair
#define all(a) (a).begin(), (a).end()
#define fillchar(a, x) memset(a, x, sizeof(a))
#define copy(a, b) memcpy(a, b, sizeof(a))
typedef long long ll;
typedef pair<int, int> pii;
typedef unsigned long long ull;
//#ifndef ONLINE_JUDGE
void RI(vector<int>&a,int n){a.resize(n);for(int i=;i<n;i++)scanf("%d",&a[i]);}
void RI(){}void RI(int&X){scanf("%d",&X);}template<typename...R>
void RI(int&f,R&...r){RI(f);RI(r...);}void RI(int*p,int*q){int d=p<q?:-;
while(p!=q){scanf("%d",p);p+=d;}}void print(){cout<<endl;}template<typename T>
void print(const T t){cout<<t<<endl;}template<typename F,typename...R>
void print(const F f,const R...r){cout<<f<<", ";print(r...);}template<typename T>
void print(T*p, T*q){int d=p<q?:-;while(p!=q){cout<<*p<<", ";p+=d;}cout<<endl;}
//#endif
template<typename T>bool umax(T&a, const T&b){return b<=a?false:(a=b,true);}
template<typename T>bool umin(T&a, const T&b){return b>=a?false:(a=b,true);}
template<typename T>
void V2A(T a[],const vector<T>&b){for(int i=;i<b.size();i++)a[i]=b[i];}
template<typename T>
void A2V(vector<T>&a,const T b[]){for(int i=;i<a.size();i++)a[i]=b[i];}
const double PI = acos(-1.0);
const int INF = 1e9 + ;
const double EPS = 1e-8;
/* -------------------------------------------------------------------------------- */
const int maxn = 2e5 + ;
struct StringHash {
const static unsigned int hack = ;
//const static int maxn = 2e5 + 7;
unsigned long long H[maxn], C[maxn];
void init(int s[], int n) {
for (int i = ; i < n; i ++) {
H[i] = (i? H[i - ] * hack : ) + s[i];
}
C[] = ;
for (int i = ; i <= n; i ++) C[i] = C[i - ] * hack;
}
unsigned long long get(int L, int R) {
return H[R] - (L? H[L - ] * C[R - L + ] : );
}
} ;
StringHash hsh, hshrev;
vector<int> G[maxn];
int a[maxn], b[maxn], F[maxn];
set<int> S;
int main() {
#ifndef ONLINE_JUDGE
freopen("in.txt", "r", stdin);
//freopen("out.txt", "w", stdout);
#endif // ONLINE_JUDGE
int T, n, cas = ;
cin >> T;
while (T --) {
cin >> n;
for (int i = ; i < n; i ++) {
scanf("%d", a + i);
}
hsh.init(a, n);
for (int i = ; i < n; i ++) b[i] = a[n - i - ];
hshrev.init(b, n);
int total = * n - ;
for (int i = ; i < total; i ++) {
int L = i / , R = (i + ) / ;
int minlen = , maxlen = min(L + , n - R);
while (minlen < maxlen) {
int midlen = (minlen + maxlen + ) >> ;
int lpos = L - midlen + , rpos = R + midlen - ;
if (hsh.get(lpos, L) == hshrev.get(n - rpos - , n - R - ))
minlen = midlen;
else maxlen = midlen - ;
}
F[i] = minlen;
}
S.clear();
for (int i = ; i < n; i ++) G[i].clear();
int ans = ;
for (int i = ; i < n - ; i ++) {
G[i - F[ * i + ] + ].pb(i);
}
for (int i = ; i < G[].size(); i ++) S.insert(G[][i]);
for (int i = ; i < total; i += ) {
int L = i / ;
for (int j = ; j < G[L + ].size(); j ++) S.insert(G[L + ][j]);
if (S.size()) {
set<int>::iterator R = S.upper_bound(L + F[i]); R --;
umax(ans, *R - L);
}
}
printf("Case #%d: %d\n", ++ cas, ans * );
}
return ;
}
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