Submission #247039

#	Time	Username	Problem	Language	Result	Execution time	Memory
247039		hackermub	Split the sequence (APIO14_sequence)	C++17	100 / 100	665 ms	84400 KiB

sequence

#include<bits/stdc++.h>
using namespace std;

#define ll long long
#define pii pair<ll,ll>
#define fi first
#define se second
#define all(v) v.begin(),v.end()
#define pb push_back
const int MOD =1e9+7;
const int64_t INF = 1e18;

vector<ll> M,C;
vector<int> L;
int last;

bool bad(int l1,int l2,int l3){
    return __int128(C[l3]-C[l1])*(M[l1]-M[l2]) < __int128(C[l2]-C[l1])*(M[l1]-M[l3]);
}

void insert(ll m,ll c,int l){
    if(!M.empty() && M.back() == m) {
        if(c>=C.back()){
            M.pop_back();
            C.pop_back();
            L.pop_back();
        }
    }
    M.push_back(m);
    C.push_back(c);
    L.push_back(l);
    while(M.size()>=3 && bad(M.size()-3,M.size()-2,M.size()-1)){
        M.erase(M.end()-2);
        C.erase(C.end()-2);
        L.erase(L.end()-2);
    }
}

ll f(int idx,ll x){
    return M[idx]*x + C[idx];
}

pii query(ll x){
    last = min(last , (int)M.size()-1);
    while(last<M.size()-1 && f(last,x)<=f(last+1,x)) last++;
    return {f(last,x),L[last]};
}

int32_t main(){
    ios_base::sync_with_stdio(false);cin.tie();
    //If you hack my code , You are gay;
    int n,K;
    cin>>n>>K;
    vector<ll> pre(n+1);
    for(int i=1;i<=n;i++){
        cin>>pre[i];
        pre[i]+=pre[i-1];
    }
    ll dp[2][n+1];
    int path[K+1][n+1];
    memset(dp,0,sizeof(dp));
    memset(path,0,sizeof(path));
    for(int k=1;k<=K;k++){
        M.clear();
        C.clear();
        L.clear();
        last=0;
        insert(0,0,0);
        for(int i=1;i<=n;i++){
            pii now = query(pre[i]);
            dp[k%2][i] = now.fi;
            path[k][i] = now.se;
            insert(pre[i],dp[!(k%2)][i]-pre[i]*pre[i],i);
        }
    }
    cout<<dp[K%2][n]<<"\n";
    vector<int> ans;
    for(int k=K;k;k--){
        n = path[k][n];
        ans.push_back(n);
    }
    reverse(all(ans));
    for(auto x:ans) cout<<x<<" ";
    return 0;
}

Compilation message (stderr)

sequence.cpp: In function 'std::pair<long long int, long long int> query(long long int)':
sequence.cpp:45:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     while(last<M.size()-1 && f(last,x)<=f(last+1,x)) last++;
           ~~~~^~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 11 / 11
• Subtask 3: 11 / 11
• Subtask 4: 17 / 17
• Subtask 5: 21 / 21
• Subtask 6: 29 / 29