Submission #1143949

#	Time	Username	Problem	Language	Result	Execution time	Memory
1143949		Shadow1	Feast (NOI19_feast)	C++20	100 / 100	131 ms	31996 KiB

feast

// Programmer: Shadow1

#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
using namespace std;

using ll = long long;
using ld = long double;
using ull = unsigned long long;
using str = string; // yay python!

#define i64 int64_t
#define show(x) cerr << (#x) << " = " << (x) << '\n';
#define output_vector(v) for(auto &x : v){cout << x << ' ';}cout << '\n';
#define output_pairvector(v) for(auto &x : v){cout << x.first << " " << x.second << '\n';}
#define read_vector(v) for(auto &x : v){cin >> x;}
#define vt vector
#define prq priority_queue
#define pb push_back
#define eb emplace_back
#define pii pair<int,int>
#define fir first
#define sec second
#define sz(x) ll(x.size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define int long long
#define discretize(x) sort(x.begin(), x.end()); x.erase(unique(x.begin(), x.end()), x.end());

// Feast trick
// What's it even called lol


void solve() {
    int n, k;
    cin >> n >> k;
    deque<int> a(n+1);
    for(int i=1; i<=n; ++i) {
        cin >> a[i];
    }
    while(!a.empty() && a.front() <= 0) a.pop_front();  // remove prefix of negs
    while(!a.empty() && a.back() <= 0) a.pop_back();  // remove suffix of negs
    bool pos = true;
    vector<int> c = {0};
    for(int i=0; i<sz(a); ++i) {   // merge pos and negs
        if((pos && a[i] >= 0) || (!pos && a[i] < 0)) 
            c.back() += a[i];
        else {
            c.push_back(a[i]);
            pos = !pos;
        }
    }
    n = sz(c);
    // output_vector(c);
    int cnt = (n+1) / 2;
    int ans = 0;
    vector<pii> range(n);
    vector<int> p(n);
    p[0] = c[0];
    for(int i=0; i<n; ++i) {
        range[i] = {i, i};
    }
    for(int i=1; i<n; ++i)
        p[i] = p[i-1] + c[i];

    auto cmp = [](pair<int, pii> &a, pair<int, pii> &b) {
        if(abs(a.fir) == abs(b.fir))
            return a.sec < b.sec;
        return abs(a.fir) > abs(b.fir);
    };

    priority_queue<pair<int, pii>, vector<pair<int, pii>>, decltype(cmp)> pq(cmp);
    for(int i=0; i<n; i++) {
        pq.push({c[i], {i, i}});
    }
    map<int, bool> vis[n];
    int s = 0, e = n-1;
    while(!pq.empty() && cnt > k) {
        int t = pq.top().fir;
        int l = pq.top().sec.fir;
        int r = pq.top().sec.sec;
        pq.pop();
        if(vis[l][r]) continue;
        vis[l][r] = true;
        // show(t);
        if(l > s) {  // combine left
            int ll = range[l-1].fir;
            int rr = range[l-1].sec;
            int d = 0;
            d += p[rr];
            if(ll > 0) d -= p[ll-1];
            vis[ll][rr] = true;
            l = ll;
            t += d;            
        }
        if(r < e) {  // combine right
            int ll = range[r+1].fir;
            int rr = range[r+1].sec;
            int d = 0;
            d += p[rr];
            if(ll > 0) d -= p[ll-1];
            vis[ll][rr] = true;
            r = rr;
            t += d;            
        }
        range[l].fir = range[r].fir = l;
        range[l].sec = range[r].sec = r;
        if(t <= 0 && l == s)
            s = l;
        else if(t <= 0 && r == e)
            e = r;
        else 
            pq.push({t, {l, r}});
        cnt--;
    }
    while(!pq.empty()) {
        if(pq.top().fir > 0 && !vis[pq.top().sec.fir][pq.top().sec.sec]) {
            ans += pq.top().fir;
            // show(pq.top().fir);
        }
        pq.pop();
    }
    cout << ans << '\n';

}



// CHECK YOUR OVERFLOWS!!!! 
signed main() {
    // freopen("output.txt", "w", stdout);
    // freopen("input.txt", "r", stdin);
    ios::sync_with_stdio(false);
    cin.tie(NULL); 
    int T = 1;
    // cin >> T;
    for(int tc = 1; tc <= T; ++tc) {
        // cout << "Case #" << tc << ": ";
        solve();
    }

    return 0;
}

• 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