Submission #528766

#	Time	Username	Problem	Language	Result	Execution time	Memory
528766		dxz05	Bigger segments (IZhO19_segments)	C++14	100 / 100	214 ms	31416 KiB

segments

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
#define MP make_pair

struct SegmentTree{
    int size = 1;
    vector<pair<int, ll>> tree;

    SegmentTree(int n){
        size = n;
        tree.resize((1 << 20) + 50);
    };

    void update(int v, int tl, int tr, int pos, pair<int, ll> val){
        if (tl == tr){
            tree[v] = max(tree[v], val);
            return;
        }
        int tm = (tl + tr) >> 1;
        if (pos <= tm) update(v << 1, tl, tm, pos, val); else
            update(v << 1 | 1, tm + 1, tr, pos, val);
        tree[v] = max(tree[v << 1], tree[v << 1 | 1]);
    }

    void update(int pos, pair<int, ll> val){
        update(1,  0, size - 1, pos, val);
    }

    pair<int, ll> get(int v, int tl, int tr, int l, int r){
        if (l <= tl && tr <= r) return tree[v];
        if (tl > r || tr < l) return MP(0, 0);
        int tm = (tl + tr) >> 1;
        return max(get(v << 1, tl, tm, l, r), get(v << 1 | 1, tm + 1, tr, l, r));
    }

    pair<int, ll> get(int l, int r){
        return get(1, 0, size - 1, l, r);
    }

};

int main() {
    ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);

    int n;
    cin >> n;

    vector<ll> pref(n);
    for (int i = 0; i < n; i++){
        cin >> pref[i];
        if (i) pref[i] += pref[i - 1];
    }

    vector<int> dp(n, 1);
    vector<ll> sum = pref;

    SegmentTree st(n);
    for (int i = 0; i < n; i++){
        auto p = st.get(0, i);

        if (p.first > dp[i] || p.second == dp[i] || pref[i] - p.second < sum[i]){
            dp[i] = p.first + 1;
            sum[i] = pref[i] - p.second;
        }

        int pos = lower_bound(pref.begin(), pref.end(), pref[i] + sum[i]) - pref.begin();

        if (pos < n) st.update(pos, MP(dp[i], pref[i]));
    }

    cout << dp[n - 1] << endl;

    return 0;
}

• Subtask 1: 13 / 13
• Subtask 2: 14 / 14
• Subtask 3: 10 / 10
• Subtask 4: 36 / 36
• Subtask 5: 27 / 27