Submission #67075

#TimeUsernameProblemLanguageResultExecution timeMemory
67075aomeCandies (JOI18_candies)C++17
0 / 100
4 ms504 KiB
#include <bits/stdc++.h> using namespace std; const int N = 200005; const long long INF = 1e18; struct Seg { int l, r; long long w; Seg (int l, int r, long long w) : l(l), r(r), w(w) {} bool operator < (const Seg& rhs) const { return w < rhs.w; } }; int n; int a[N]; long long res; long long sum[2][N]; vector<Seg> vec; set< pair<int, int> > s; priority_queue<Seg> pq1, pq2; int main() { ios::sync_with_stdio(false); cin >> n; for (int i = 1; i <= n; ++i) { cin >> a[i]; sum[0][i] = sum[0][i - 1] + a[i] * (i % 2 == 0); sum[1][i] = sum[1][i - 1] + a[i] * (i % 2 == 1); pq1.push(Seg(i, i, a[i])); } for (int i = 1; i <= (n + 1) / 2; ++i) { long long v1 = -INF, v2 = -INF; while (pq1.size()) { long long w = pq1.top().w; int p = pq1.top().l; auto it = s.lower_bound(make_pair(p + 2, 0)); if (it != s.begin() && (--it) -> second + 1 >= p) pq1.pop(); else { v1 = w; break; } } while (pq2.size()) { long long w = pq2.top().w; int l = pq2.top().l, r = pq2.top().r; if (s.find(make_pair(l, r)) == s.end()) pq2.pop(); else { v2 = w; break; } } if (v1 >= v2) { int p = pq1.top().l; pq1.pop(); int l = p, r = p; auto it = s.lower_bound(make_pair(p, 0)); if (it != s.end() && (it -> first) == r + 2) { r = (it -> second), s.erase(it); } it = s.lower_bound(make_pair(p, 0)); if (it != s.begin() && (--it) -> second == l - 2) { l = (it -> first), s.erase(it); } bool t = l % 2; if (l > 1 && r < n) { pq2.push(Seg(l, r, (sum[t ^ 1][r + 1] - sum[t ^ 1][l - 2]) - (sum[t][r] - sum[t][l - 1]))); s.insert(make_pair(l, r)); } res += v1; } else { int l = pq2.top().l, r = pq2.top().r; pq2.pop(); s.erase(s.find(make_pair(l, r))); l--, r++; bool t = l % 2; if (l > 1 && r < n) { pq2.push(Seg(l, r, (sum[t ^ 1][r + 1] - sum[t ^ 1][l - 2]) - (sum[t][r] - sum[t][l - 1]))); s.insert(make_pair(l, r)); } res += v2; } cout << res << '\n'; } }
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