108 lines
2.3 KiB
C++
108 lines
2.3 KiB
C++
/* Problem URL: https://codeforces.com/problemset/problem/1826/D */
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#include <bits/stdc++.h>
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using namespace std;
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#define V vector
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#define rmin(a, b) a = min(a, b)
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#define rmax(a, b) a = max(a, b)
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#define rep(i, lim) for (int i = 0; i < (lim); i++)
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#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
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#define repv(i, v) for (auto &i : (v))
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#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
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#define sortv(v) sort(v.begin(), v.end())
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#define all(v) (v).begin(), (v).end()
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using vi = vector<int>;
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using vvi = vector<vi>;
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using vvvi = vector<vvi>;
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using vvvvi = vector<vvvi>;
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using ll = long long;
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using vl = vector<ll>;
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using vvl = vector<vl>;
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using vvvl = vector<vvl>;
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using vvvvl = vector<vvvl>;
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template<class v>
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auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
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os << vec[0];
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for (size_t i = 1; i < vec.size(); i++) {
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os << ' ' << vec[i];
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}
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os << '\n';
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return os;
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}
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template<class v>
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auto operator>>(istream &is, vector<v> &vec)->istream& {
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for (auto &i : vec) {
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is >> i;
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}
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return is;
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}
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template<class v>
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auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
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for (auto &i : vec) {
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os << i[0];
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for (size_t j = 1; j < i.size(); j++) {
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os << ' ' << i[j];
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}
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os << '\n';
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}
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return os;
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}
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template<class v>
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auto operator>>(istream &is, vector<vector<v>> &vec)->istream& {
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for (auto &i : vec) {
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for (auto &j : i) {
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is >> j;
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}
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}
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return is;
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}
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int main()
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{
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ios::sync_with_stdio(false);
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cin.tie(nullptr);
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int t;
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cin >> t;
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while (t--) {
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int n;
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cin >> n;
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vl fds(n);
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cin >> fds;
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V<pair<ll, int>> suf(n);
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V<pair<ll, int>> pref(n);
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auto maxi = [&](pair<ll, int> a, pair<ll, int> b) {
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return a.first - abs(a.second - b.second) > b.first ? a : b;
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};
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pref[0] = {fds[0], 0};
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suf.back() = {fds.back(), n - 1};
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nrep(i, 1, n) {
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pref[i] = maxi(pref[i - 1], {fds[i], i});
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suf[n - i - 1] = maxi(suf[n - i], {fds[n - i - 1], n - i - 1});
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}
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ll ans = 0;
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nrep(i, 1, n - 1) {
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rmax(ans, fds[i] + pref[i - 1].first + suf[i + 1].first - suf[i + 1].second + pref[i - 1].second);
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}
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cout << ans << '\n';
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}
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}
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