Problem p03611 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <algorithm>
#include <bitset>
#include <cassert>
#include <ciso646>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstring>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ul;
typedef unsigned int ui;
typedef long double ld;
const ll mod = 1000000007;
const ll INF = mod * mod;
#define rep(i, n) for (int i = 0; i < n; i++)
#define per(i, n) for (int i = n - 1; i >= 0; i--)
#define Rep(i, sta, n) for (int i = sta; i < n; i++)
#define rep1(i, n) for (int i = 1; i <= n; i++)
#define per1(i, n) for (int i = n; i >= 1; i--)
#define Rep1(i, sta, n) for (int i = sta; i <= n; i++)
typedef complex<ld> Point;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<int, int> P;
typedef pair<ld, ld> LDP;
typedef pair<ll, ll> LP;
typedef vector<int> vec;
typedef vector<string> svec;
#define fr first
#define sc second
#define all(c) c.begin(), c.end()
#define pb push_back
// #define int long long

void solve() {
  int N;
  cin >> N;
  int a[100100];
  map<int, int> mp;
  rep(i, N) {
    cin >> a[i];
    mp[a[i]]++;
  }
  int res = 0;
  for (auto p : mp) {
    int n = p.fr;
    int cnt = mp[n - 1] + mp[n] + mp[n + 1];
    if (cnt >= res)
      res = cnt;
  }
  cout << res << endl;
}

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  // cout << fixed << setprecision(10);
  // init();
  solve();
  // cout << "finish" << endl;
  return 0;
}

Fixed submission:
#include <algorithm>
#include <bitset>
#include <cassert>
#include <ciso646>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstring>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ul;
typedef unsigned int ui;
typedef long double ld;
const ll mod = 1000000007;
const ll INF = mod * mod;
#define rep(i, n) for (int i = 0; i < n; i++)
#define per(i, n) for (int i = n - 1; i >= 0; i--)
#define Rep(i, sta, n) for (int i = sta; i < n; i++)
#define rep1(i, n) for (int i = 1; i <= n; i++)
#define per1(i, n) for (int i = n; i >= 1; i--)
#define Rep1(i, sta, n) for (int i = sta; i <= n; i++)
typedef complex<ld> Point;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<int, int> P;
typedef pair<ld, ld> LDP;
typedef pair<ll, ll> LP;
typedef vector<int> vec;
typedef vector<string> svec;
#define fr first
#define sc second
#define all(c) c.begin(), c.end()
#define pb push_back
// #define int long long

void solve() {
  int N;
  cin >> N;
  int a[100100];
  map<int, int> mp;
  rep(i, N) {
    cin >> a[i];
    mp[a[i]]++;
  }
  int res = 0;
  rep(i, N) {
    int cnt = mp[a[i] - 1] + mp[a[i]] + mp[a[i] + 1];
    res = max(res, cnt);
  }
  cout << res << endl;
}

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  // cout << fixed << setprecision(10);
  // init();
  solve();
  // cout << "finish" << endl;
  return 0;
}