Submission #669792

#	Time	Username	Problem	Language	Result	Execution time	Memory
669792		Dan4Life	Split the sequence (APIO14_sequence)	C++17	0 / 100	18 ms	31960 KiB

sequence

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
#define all(a) a.begin(),a.end()
#define mp make_pair
#define fi first
#define se second
#define sz(a) (int)a.size()
const int maxn = (int)1e4+10;
const int INF = (int)2e18;
int n, K, a[maxn], pre[maxn];
int dp[maxn][201], p[maxn][201];
vector<int> v;
 
void recur(int i, int k){ if(k) v.pb(i), recur(p[i][k],k-1); }
 
double slope(int i, int j, int k){
    if(dp[i][k]<0) return INF;
    //if(i>j)swap(i,j); if(i==0) return (double)dp[j][k]/pre[j];
    return (double)(dp[i][k]-dp[j][k])/(pre[i]-pre[j]);
}

int32_t main()
{
    ios_base::sync_with_stdio(false); cin.tie(0);
    cin >> n >> K; int ans = -(int)1e18, st=-1;
    for(int i = 0; i < n; i++) cin >> a[i], pre[i+1]=pre[i]+a[i];
    for(int i = 0; i <= n; i++)
        for(int k = 0; k <= K+1; k++)
            dp[i][k]=(k==0?0:-INF);
    for(int k = 1; k <= K+1; k++){
        deque<int> DQ; DQ.clear(); DQ.push_back(0);
        for(int i = 1; i <= n; i++){
            while(sz(DQ)>1 and slope(DQ[0],DQ[1],k-1)>=pre[n]-pre[i]) DQ.pop_front();
            int j = DQ[0]; int tot = dp[j][k-1]+(pre[i]-pre[j])*(pre[n]-pre[i]);
            if(dp[i][k] < tot) dp[i][k]=tot, p[i][k]=j;
            while(sz(DQ)>1 and slope(DQ[sz(DQ)-2], DQ.back(),k-1) <= slope(DQ.back(),i,k-1)) DQ.pop_back();
            DQ.push_back(i);
        }
    }
    cout << dp[n][K+1] << "\n"; recur(n,K+1);
    sort(all(v)); v.pop_back(); for(auto u : v) cout << u << " ";
}

Compilation message (stderr)

sequence.cpp: In function 'int32_t main()':
sequence.cpp:27:24: warning: unused variable 'ans' [-Wunused-variable]
   27 |     cin >> n >> K; int ans = -(int)1e18, st=-1;
      |                        ^~~
sequence.cpp:27:42: warning: unused variable 'st' [-Wunused-variable]
   27 |     cin >> n >> K; int ans = -(int)1e18, st=-1;
      |                                          ^~

• Subtask 1: 0 / 11
• Subtask 2: 0 / 11
• Subtask 3: 0 / 11
• Subtask 4: 0 / 17
• Subtask 5: 0 / 21
• Subtask 6: 0 / 29