Submission #791750

#	Time	Username	Problem	Language	Result	Execution time	Memory
791750		minhnhatnoe	Feast (NOI19_feast)	C++14	100 / 100	93 ms	7392 KiB

feast

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
vector<ll> a;

pair<ll, int> choose(pair<ll, int> a, pair<ll, int> b){
    if (a.first == b.first) return min(a, b);
    return max(a, b);
}
pair<ll, int> calc(ll bm){
    int n = a.size();
    pair<ll, int> pfmax(0, 0);
    pair<ll, int> prevdp(0, 0);
    for (int i=0; i<n; i++){
        // dp[i] = max(dp[i-1], dp[k-1] + pf[i] - pf[k-1] - bm)
        //                      (dp[k-1] - pf[k-1]) + pf[i] - bm
        pair<ll, int> cdp = prevdp;
        cdp = choose(cdp, pair<ll, int> (pfmax.first + a[i] - bm,
            pfmax.second + 1));
        pfmax = choose(pfmax, pair<ll, int> (cdp.first - a[i], cdp.second));
        prevdp = cdp;
    }
    return prevdp;
}
signed main(){
    cin.tie(0)->sync_with_stdio(0);
    int n, k; cin >> n >> k;
    a.resize(n);
    for (int i=0; i<n; i++) cin >> a[i];
    partial_sum(a.begin(), a.end(), a.begin());

    ll bl=0, br=1e18;
    vector<pair<ll, int>> dp(n);
    while (bl < br){
        ll bm = (bl + br) >> 1;
        if (calc(bm).second > k) bl = bm+1;
        else br = bm;
    }
    pair<ll, int> s = calc(bl);
    cout << s.first + k * bl << "\n";
}

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 10 / 10
• Subtask 5: 11 / 11
• Subtask 6: 20 / 20
• Subtask 7: 29 / 29