제출 #790500

#제출 시각아이디문제언어결과실행 시간메모리
790500AlcabelAliens (IOI16_aliens)C++17
100 / 100
126 ms13000 KiB
#include <bits/stdc++.h> #ifndef LOCAL #include "aliens.h" #endif using namespace std; struct Line { int a; long long b; Line() {} Line(int _a, long long _b) { a = _a, b = _b; } long long f(int x) { return a * 1ll * x + b; } ~Line() {} }; int sign(long long x) { if (x > 0) { return 1; } if (x < 0) { return -1; } return 0; } long long intersect(const Line& A, const Line& B) { // x = (B.b - A.b) / (A.a - B.a) long long numer = B.b - A.b, denom = A.a - B.a; int sn = sign(numer), sd = sign(denom); numer *= sn, denom *= sd; if (sn * sd < 0) { return numer / denom * -1; } return (numer + denom - 1) / denom; } long long take_photos(int n, int m, int k, vector<int> rows, vector<int> cols) { vector<int> maxRight(m, -1); for (int i = 0; i < n; ++i) { int l = min(rows[i], cols[i]); int r = max(rows[i], cols[i]); maxRight[l] = max(maxRight[l], r + 1); } vector<pair<int, int>> segs; for (int l = 0; l < m; ++l) { if (maxRight[l] != -1 && (segs.empty() || segs.back().second < maxRight[l])) { segs.emplace_back(l, maxRight[l]); } } n = segs.size(); /*for (const auto& [l, r] : segs) { cerr << l << ' ' << r << '\n'; }*/ k = min(k, n); vector<pair<long long, int>> dp(n); vector<Line> lines; vector<long long> optX; vector<int> cntSegs; auto compute = [&](long long lambda) -> int { lines = {}; optX = {}; cntSegs = {}; dp[0] = {(segs[0].second - segs[0].first) * 1ll * (segs[0].second - segs[0].first) + lambda, 1}; for (int i = 1, ptr = 0; i < n; ++i) { // cerr << "i: " << i << '\n'; int lenInter = max(0, segs[i - 1].second - segs[i].first); Line l(-2 * segs[i].first, dp[i - 1].first - lenInter * 1ll * lenInter + segs[i].first * 1ll * segs[i].first); while (!lines.empty() && intersect(lines.back(), l) <= optX.back()) { optX.pop_back(); lines.pop_back(); cntSegs.pop_back(); } if (!lines.empty()) { optX.emplace_back(intersect(lines.back(), l)); } else { optX.emplace_back(-1); } lines.emplace_back(l); cntSegs.emplace_back(dp[i - 1].second); // cerr << "inserted!\n"; ptr = min(ptr, (int)lines.size() - 1); while (ptr + 1 < (int)lines.size() && optX[ptr + 1] <= segs[i].second) { ++ptr; } // cerr << "found!\n"; dp[i] = {lines[ptr].f(segs[i].second) + segs[i].second * 1ll * segs[i].second + lambda, cntSegs[ptr] + 1}; if ((segs[i].second - segs[0].first) * 1ll * (segs[i].second - segs[0].first) + lambda < dp[i].first) { dp[i] = {(segs[i].second - segs[0].first) * 1ll * (segs[i].second - segs[0].first) + lambda, 1}; } // cerr << "i: " << i << ", dp: " << dp[i].first << ' ' << dp[i].second << '\n'; } return dp[n - 1].second; }; long long left = -1, right = m * 1ll * m + 10; while (right - left > 1) { long long mid = left + (right - left) / 2; // cerr << "mid: " << mid << '\n'; int res = compute(mid); // cerr << "res: " << res << '\n'; if (res >= k) { left = mid; } else { right = mid; } } compute(left); // cerr << "right: " << right << '\n'; // cerr << "dp: " << dp[n - 1].first << ", " << dp[n - 1].second << '\n'; return dp[n - 1].first - k * left; } /* void solve() { int n, m, k; cin >> n >> m >> k; vector<int> r(n), c(n); for (int i = 0; i < n; ++i) { cin >> r[i] >> c[i]; } cout << take_photos(n, m, k, r, c) << '\n'; } int main() { ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); #ifdef LOCAL freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout); int T = 1; cin >> T; while (T--) { solve(); cerr << "-----------\n"; cout << "-----------\n"; } #else int T = 1; cin >> T; while (T--) { solve(); } #endif return 0; } */
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