每日構造/DP(4.20)
阿新 • • 發佈:2022-04-22
#include <bits/stdc++.h> #define IOS \ std::ios::sync_with_stdio(false); \ std::cin.tie(0); \ std::cout.tie(0); using ll = long long; const ll inf = 1e18; #define lson o << 1 #define rson o << 1 | 1 struct SegTree { const int n; std::vector<ll> max; SegTree(int n) : n(n), max(n << 2 | 1, -inf){}; void pushup(int o) { max[o] = std::max(max[lson], max[rson]); } void update(int o, int l, int r, int x, ll y) { if (r < x || x < l) return; if (l == x && r == x) { max[o] = std::max(max[o], y); return; } int mid = (l + r) >> 1; if (x <= mid) update(lson, l, mid, x, y); if (x > mid) update(rson, mid + 1, r, x, y); pushup(o); } ll query(int o, int l, int r, int x, int y) { if (r < x || y < l) return -inf; if (x <= l && r <= y) return max[o]; int mid = l + r >> 1; return std::max(query(lson, l, mid, x, y), query(rson, mid + 1, r, x, y)); } }; ll solve() { int n; std::cin >> n; std::vector<ll> a(n + 1), s(n + 1), ss(n + 1), f(n + 1, -inf); for (int i = 1; i <= n; ++i) std::cin >> a[i]; for (int i = 1; i <= n; ++i) ss[i] = s[i] = s[i - 1] + a[i]; std::sort(ss.begin(), ss.end()); ss.erase(std::unique(ss.begin(), ss.end()), ss.end()); for (int i = 0; i <= n; ++i) s[i] = std::lower_bound(ss.begin(), ss.end(), s[i]) - ss.begin() + 1; int nn = ss.size(); SegTree t[3] = {nn, nn, nn}; // f[i] - i, f[i], f[i] + i for (int i = 0; i < 3; ++i) t[i].update(1, 1, nn, s[0], 0); for (int i = 1; i <= n; ++i) { f[i] = std::max({t[0].query(1, 1, nn, 1, s[i] - 1) + i, t[1].query(1, 1, nn, s[i], s[i]), t[2].query(1, 1, nn, s[i] + 1, nn) - i}); t[0].update(1, 1, nn, s[i], f[i] - i); t[1].update(1, 1, nn, s[i], f[i]); t[2].update(1, 1, nn, s[i], f[i] + i); } return f[n]; } int main() { IOS; int t; std::cin >> t; while (t--) std::cout << solve() << std::endl; return 0; }
#include <bits/stdc++.h> #define PII std::pair<int, int> int main() { int n, m, nn; std::cin >> n; std::vector<PII> ans; if (n == 1) { std::cout << "1\n1 1" << std::endl; return 0; } if (n % 3 == 0) m = n / 3; else if ((n - 1) % 3 == 0) m = (n - 1) / 3; else m = (n + 1) / 3; for (int i = 1; i <= m; ++i) ans.push_back({i, m - i + 1}); for (int i = 1; i <= m - 1; ++i) ans.push_back({m + i, 2 * m - i}); if (n % 3 == 0) { ans.push_back({n, n}); } else if ((n - 1) % 3 == 0) { ans.push_back({n - 1, n - 1}); ans.push_back({n, n}); } std::cout << ans.size() << std::endl; for (auto [x, y] : ans) std::cout << x << " " << y << std::endl; return 0; }