提出 #60963980

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ソースコード 拡げる

#include <algorithm>
#include <atcoder/all>
#include <cassert>
#include <chrono>
#include <cmath>
#include <complex>
#include <cstdint>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <queue>
#include <random>
#include <regex>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vll = vector<ll>;
using vvll = vector<vector<ll>>;
using vvvll = vector<vector<vector<ll>>>;
using vii = vector<int>;
using vvii = vector<vector<int>>;
using vvvii = vector<vector<vector<int>>>;
using vdd = vector<ld>;
using vvdd = vector<vector<ld>>;
using vvvdd = vector<vector<vector<ld>>>;
using vbb = vector<bool>;
using vvbb = vector<vector<bool>>;
using vvvbb = vector<vector<vector<bool>>>;
using vpll = vector<pll>;
using vvpll = vector<vector<pll>>;
using vvvpll = vector<vector<vector<pll>>>;
using vmm1 = vector<modint1000000007>;
using vvmm1 = vector<vector<modint1000000007>>;
using vvvmm1 = vector<vector<vector<modint1000000007>>>;
using vmm2 = vector<modint998244353>;
using vvmm2 = vector<vector<modint998244353>>;
using vvvmm2 = vector<vector<vector<modint998244353>>>;
#define pb push_back
#define mp make_pair
#define sc second
#define fr first
#define endl '\n'
#define stpr std::fixed << setprecision
#define cYES cout << "YES" << endl
#define cNO cout << "NO" << endl
#define cYes cout << "Yes" << endl
#define cNo cout << "No" << endl
#define cerr cout << -1 << endl
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define drep(i, a, b, d) for (ll i = (a); i <= (b); i += d)
#define Rep(i, a, b) for (ll i = (a); i < (b); ++i)
#define rrep(i, n) for (ll i = n - 1; i >= 0; i--)
#define drrep(i, a, b, d) for (ll i = (a); i >= (b); i -= d)
#define rRep(i, a, b) for (ll i = a; i >= b; i--)
#define crep(i) for (char i = 'a'; i <= 'z'; ++i)
#define Crep(i) for (char i = 'A'; i <= 'Z'; ++i)
#define ALL(x) (x).begin(), (x).end()
#define rALL(x) (x).rbegin(), (x).rend()
#define sort2(A, N) \
  sort(A, A + N,    \
       [](const pii &a, const pii &b) { return a.second < b.second; });
#define debug(v)      \
  cout << #v << ":";  \
  for (auto x : v) {  \
    cout << x << ' '; \
  }                   \
  cout << endl;
int ctoi(const char c) {
  if ('0' <= c && c <= '9') return (c - '0');
  return -1;
}
ll gcd(ll a, ll b) { return (b == 0 ? a : gcd(b, a % b)); }
ll lcm(ll a, ll b) { return a * b / gcd(a, b); }
ll rup(ll a, ll b) { return a + (b - a % b) % b; }
ll rdc(ll a, ll b) { return a / b * b; }
constexpr ll INF = 1000000011;
constexpr ll MOD = 1000000007;
constexpr ll MOD2 = 998244353;
constexpr ll LINF = 1001002003004005006ll;
constexpr ld EPS = 10e-15;
using mint = modint998244353;
using mint2 = modint1000000007;
template <class T, class U>
inline bool chmax(T &lhs, const U &rhs) {
  if (lhs < rhs) {
    lhs = rhs;
    return 1;
  }
  return 0;
}
template <class T, class U>
inline bool chmin(T &lhs, const U &rhs) {
  if (lhs > rhs) {
    lhs = rhs;
    return 1;
  }
  return 0;
}
template <typename T>
istream &operator>>(istream &is, vector<T> &v) {
  for (auto &&x : v) is >> x;
  return is;
}
template <typename T, typename U>
istream &operator>>(istream &is, pair<T, U> &p) {
  is >> p.first;
  is >> p.second;
  return is;
}
template <typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
  os << p.first << ' ' << p.second;
  return os;
}
template <class T>
ostream &operator<<(ostream &os, vector<T> &v) {
  for (auto i = begin(v); i != end(v); ++i) {
    if (i != begin(v)) os << ' ';
    os << *i;
  }
  return os;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  ll n;cin >> n;
  vll h(n);
  rep(i,n) cin >> h[i];

    map<ll,vll> pos; // 高さと位置
    rep(i,n) pos[h[i]].pb(i);

    ll ans = 1; // 1つのビル
    for(auto p : pos) {
      auto v = p.second; // 同じ高さのビルの位置
      ll m = v.size();

      if(m == 1) continue; // ビル一つ

      // dp[i][d]:= v[i]を末尾の時の公差dの等差数列の長さ
      vector<map<ll,ll>> dp(m);
      
      rep(i,m) { // 各ビル
        rep(j,i) { // それより前のビル
          ll diff = v[i] - v[j];
          if(dp[j].count(diff)) { // v[j]が末尾でdiffの等差数列があれば延長　なければその2つ
            dp[i][diff] = dp[j][diff] + 1;
          } else {
            dp[i][diff] = 2;
          }
          chmax(ans,dp[i][diff]);
        }
      }
    }

    cout << ans << "\n";
}

提出情報

ジャッジ結果