Submission #1103141

#TimeUsernameProblemLanguageResultExecution timeMemory
1103141DuongKietFeast (NOI19_feast)C++17
0 / 100
1071 ms21464 KiB
#include <bits/stdc++.h> #define N 300005 #define inf 100000000000000000LL #define ll long long #define int long long #define ii pair <int,long long> #define fi first #define se second #define all(x) x.begin(),x.end() #define pb push_back using namespace std; const unsigned ll Mod = 1000000007LL; int n, k, a[N]; void init(){ cin >> n >> k; for (int i = 1; i <= n; i++) cin >> a[i]; } bool ifsub1(){ for (int i = 1; i <= n; i++) if (a[i] < 0) return 0; return 1; } void sub1(){ int ans = 0; for (int i = 1; i <= n; i++) ans += a[i]; cout << ans << '\n'; } int pos; bool ifsub2(){ int cnt = 0; for (int i = 1; i <= n; i++) if (a[i] < 0) {pos = a[i]; cnt++;} return (cnt < 2); } void sub2(){ int sum = 0, suml = 0, am = 0; bool kt = 0; for (int i = 1; i <= n; i++){ if (a[i] < 0) { kt = 1; am = a[i]; } if (!kt) suml += a[i]; sum += a[i]; } if (k > 1) cout << sum - am << '\n'; else cout << max(suml, max(sum, sum - suml - am)); } void sub3(){ int ans = 0, res = 0; for (int i = 1; i <= n; i++) { res = max(0ll, res + a[i]); ans = max(ans, res); } cout << ans << '\n'; } //int pa[N], sz[N]; //int findpa(int u){ // // if (u == pa[u]) return u; // return pa[u] = findpa(pa[u]); //} //void Union(int a, int b){ // // a = findpa(a); // b = findpa(b); // if (a == b) return; // if (sz[a] < sz[b]) swap(a,b); // pa[b] = a; // sz[a] += sz[b]; // sum[a] += sum[b]; //} //vector <ii> d; //void Add(int u){ // d.pb({u, sum[u]}); //} //void sub6(){ // for (int i = 1; i <= n; i++){ // pa[i] = i; // sz[i] = 1; // sum[i] = a[i]; // } // int parduong, param; // bool task = 0; // if (a[1] >= 0) {parduong = 1; task = 1;} // else param = 1; // for (int i = 1; i <= n; i++){ // if (a[i] >= 0) { // if (task) // Union(parduong, i); // else parduong = i; // task = 1; // } // else { // if (!task) Union(param, i); // else param = i; // task = 0; // } // } // int curpa = findpa(1); // Add(curpa); // for (int i = 1; i <= n; i++){ // int u = findpa(i); // if (u != curpa){ // curpa = u; // Add(u); // } // } // for (int i = 2; i < d.size(); i++){ // if (d[i].se > 0 && d[i-2].se > 0){ // g.pb({d[i].fi, d[i - 2].fi, d[i].se + d[i].se }); // } // } //} pair<long double, int> dp[N + 1][2]; bool check(long double res) { dp[0][0] = {0, 0}, dp[0][1] = {-inf, 0}; for (int i = 1; i <= n; ++i) { dp[i][0] = max(dp[i - 1][0], dp[i - 1][1]); dp[i][1] = max(make_pair(dp[i - 1][1].first + a[i], dp[i - 1][1].second), make_pair(dp[i - 1][0].first + a[i] - res, dp[i - 1][0].second + 1)); } return max(dp[n][0], dp[n][1]).second >= k; }; void solve(){ const long double EPS = 1e-3; int lower = 0, upper = inf; while (lower + EPS < upper) { int mid = (lower + upper) / 2; if (check(mid)) { lower = mid; } else { upper = mid; } } int res = lower; check(res); cout << res * k + max(dp[n][0].first, dp[n][1].first); } signed main() { ios_base::sync_with_stdio(false); cin.tie(0);cout.tie(0); #define nametask "PRESUFF" if(fopen(nametask".inp", "r")) { freopen(nametask".inp", "r", stdin); freopen(nametask".out", "w", stdout); } init(); // if (ifsub1()) return sub1(), 0; // if (ifsub2()) return sub2(), 0; // if (k == 1) return sub3(), 0; // if (k <= n && n <= 2000) return sub6(), 0; solve(); return 0; } /// Duong Anh Kiet from Kien Giang /// /* 6 1 -1 -2 -1 2 -1 2 */

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:159:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  159 |         freopen(nametask".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:160:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  160 |         freopen(nametask".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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