func_code_string: #include <bits/stdc++.h>   using namespace std;   const char nl =   n ;   const int MAX_N = 100011;   const long long INF = (1 << 29) + 123;   const long long MOD = 1000000007;   const long double PI = 4 * atan((long double)1);   template <typename T>   bool ckmin(T& a, const T& b) {     return a > b ? a = b, 1 : 0;   }   template <typename T>   bool ckmax(T& a, const T& b) {     return b > a ? a = b, 1 : 0;   }   void dbg_out() { cerr << endl; }   template <typename Head, typename... Tail>   void dbg_out(Head H, Tail... T) {     cerr << H <<    ;     dbg_out(T...);   }   mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());   const int MX = 1 << 20;   int main() {     ios_base::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);     int n;     cin >> n;     int m = n;     vector<int> LOC[n + 1];     int A[n];     for (int i = 0; i < n; i++) {       cin >> A[i];       LOC[A[i]].push_back(i);     }     int hi = 0, best = -1;     for (int i = 1; i <= m; i++)       if (ckmax(hi, (int)LOC[i].size())) best = i;     bool done = 0;     for (int i = 1; i <= m; i++)       if (i != best && hi == (int)LOC[i].size()) done = 1;     if (done) {       cout << n << nl;       return 0;     }     n += 2;     int a[n];     for (int i = 0; i < n - 2; i++) a[i + 1] = A[i];     a[0] = a[n - 1] = best;     vector<int> loc[n + 1];     for (int i = 0; i < n; i++) loc[a[i]].push_back(i);     hi = (int)loc[best].size();     int idxBest[n];     for (int i = 0; i < n; i++)       if (i == 0)         idxBest[i] = 1;       else         idxBest[i] = idxBest[i - 1] + (a[i] == best);     int ans = 0;     int SQRTN = sqrt(n) - 100;     for (int i = 1; i <= m; i++) {       int SZ = (int)loc[i].size();       if (i == best || !SZ) continue;       if (SZ > SQRTN) {         int j = 0, k = 0;         int sum = 0;         int firstLoc[2 * n + 1];         for (int ii = 0; ii < 2 * n + 1; ii++) firstLoc[ii] = -1;         firstLoc[sum + n] = 0;         while (j != hi - 1 || k != SZ) {           int curPos;           if (k < SZ && loc[best][j] > loc[i][k]) {             curPos = loc[i][k] + 1;             ckmax(ans, curPos - 1 - firstLoc[sum + n]);             sum++;             k++;           } else {             curPos = loc[best][j] + 1;             ckmax(ans, curPos - 1 - firstLoc[sum + n]);             sum--;             j++;           }           if (firstLoc[sum + n] == -1) firstLoc[sum + n] = curPos;         }         ckmax(ans, loc[best][j] - firstLoc[sum + n]);       } else {         int kkk = 0;         for (int kk = 0; kk < SZ; kk++) {           int j = max(0, idxBest[loc[i][kk]] - SZ - 2);           int jEnd = min(hi, idxBest[loc[i][kk]] + SZ + 2);           while (kkk < SZ && loc[best][j] > loc[i][kkk]) kkk++;           int k = kkk;           int PAD = 2 * SZ + 5;           int firstLoc[2 * PAD + 1];           for (int ii = 0; ii < 2 * PAD + 1; ii++) firstLoc[ii] = -1;           int sum = -1;           if (j == 0) firstLoc[0 + PAD] = 0;           firstLoc[sum + PAD] = loc[best][j] + 1;           j++;           while (j < jEnd) {             int curPos;             if (k < SZ && loc[i][k] < loc[best][j]) {               curPos = loc[i][k] + 1;               ckmax(ans, loc[i][k] - firstLoc[sum + PAD]);               sum++;               k++;             } else {               curPos = loc[best][j] + 1;               ckmax(ans, loc[best][j] - firstLoc[sum + PAD]);               sum--;               j++;             }             if (firstLoc[sum + PAD] == -1) firstLoc[sum + PAD] = curPos;           }           if (j != hi) ckmax(ans, loc[best][j] - firstLoc[sum + PAD]);         }       }     }     cout << ans << nl;     return 0;   }   