Submission #869330

#TimeUsernameProblemLanguageResultExecution timeMemory
869330prohackerSplit the sequence (APIO14_sequence)C++14
0 / 100
25 ms131072 KiB
#include <bits/stdc++.h> #define ll long long #define ld long double #define int long long using namespace std; const int N = 1e5+10; const int INF = INT_MAX; const int mod = 1e9+7; int n,m; ll dp[N][205],ans; int s[N],trace[N][205]; stack<int> st; int pointer; vector<ll> M; vector<ll> B; vector<int> idx; bool bad(int l1,int l2,int l3) { return (ld)(B[l3]-B[l1])/(B[l2]-B[l1]) < (ld)(M[l1]-M[l3])/(M[l1]-M[l2]); } void add(ll m,ll b, int id) { M.push_back(m); B.push_back(b); idx.push_back(id); while(M.size() >= 3 and bad(M.size()-3,M.size()-2,M.size()-1)) { M.erase(M.end()-2); B.erase(B.end()-2); idx.erase(idx.end()-2); } } pair<ll,int> query(ll x) { if (pointer >= M.size()) { pointer = M.size()-1; } while(pointer < M.size()-1 and 1LL*M[pointer+1]*x+B[pointer+1] > 1LL*M[pointer]*x+B[pointer]) { pointer++; } return {1LL*M[pointer]*x+B[pointer],idx[pointer]}; } signed main() { if (fopen("task.inp", "r")) { freopen("task.inp", "r", stdin); freopen("task.out", "w", stdout); } ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); cin >> n >> m; for(int i = 1 ; i <= n ; i++) { int x; cin >> x; s[i] = s[i-1] + x; } for(int k = 1 ; k <= m ; k++) { for(int i = 1 ; i <= n ; i++) { add(s[i-1],dp[i-1][k-1]-1LL*s[i-1]*s[n],i-1); pair<ll,int> val = query(s[i]); dp[i][k] = val.first+1LL*s[i]*(s[n]-s[i]); trace[i][k] = val.second; // for(int j = i-1 ; j >= 0 ; j--) { // if(dp[j][k-1]+1LL*(s[i]-s[j])*(s[n]-s[i]) > dp[i][k]) { // dp[i][k] = dp[j][k-1]+1LL*(s[i]-s[j])*(s[n]-s[i]); // trace[i][k] = j; // } // } } B.clear(); M.clear(); idx.clear(); pointer = 0; } int id; ans = -1; for(int i = 1 ; i <= n ; i++) { if(dp[i][m] > ans) { ans = dp[i][m]; id = i; } } cout << ans << '\n'; while(m > 0) { cout << id << " "; id = trace[id][m]; m--; } return 0; }

Compilation message (stderr)

sequence.cpp: In function 'std::pair<long long int, long long int> query(long long int)':
sequence.cpp:37:17: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   37 |     if (pointer >= M.size()) {
      |         ~~~~~~~~^~~~~~~~~~~
sequence.cpp:40:19: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   40 |     while(pointer < M.size()-1 and 1LL*M[pointer+1]*x+B[pointer+1] > 1LL*M[pointer]*x+B[pointer]) {
      |           ~~~~~~~~^~~~~~~~~~~~
sequence.cpp: In function 'int main()':
sequence.cpp:49:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   49 |         freopen("task.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
sequence.cpp:50:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   50 |         freopen("task.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
sequence.cpp:89:12: warning: 'id' may be used uninitialized in this function [-Wmaybe-uninitialized]
   89 |         id = trace[id][m];
      |         ~~~^~~~~~~~~~~~~~
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