codeforces 333, div2 b

cf_333_d2_b.cpp

// Kinda long solution
// Complexity - nlogn
#include <bits/stdc++.h>
using namespace std;

int getLargestAConst(const vector<int>& a) {
    int maxL = 0;
    int l = 0, r = 0;
    map<int, int> subseq;
    while (r != a.size()) {
        if (l == r) {
            if (subseq.count(a[r]) == 0)
                subseq.emplace(a[r], 1);
            else
                ++subseq[a[r]];
            ++r;
        } else if (subseq.rbegin()->first - subseq.begin()->first <= 1) {
            maxL = max(maxL, r - l);

            if (subseq.count(a[r]) == 0)
                subseq.emplace(a[r], 1);
            else
                ++subseq[a[r]];
            ++r;
        } else {
            --subseq[a[l]];
            if (subseq[a[l]] == 0)
                subseq.erase(subseq.find(a[l]));
            ++l;
        }
    }
    if (subseq.rbegin()->first - subseq.begin()->first <= 1)
        return max(maxL, r - l);
    return maxL;
}

int main(int, char**) {
    int n;
    cin >> n;

    vector<int> a(n);
    for (int i = 0; i < n; ++i)
        cin >> a[i];

    cout << getLargestAConst(a) << "\n";

    return 0;
}