Submission #1204988

#	Time	Username	Problem	Language	Result	Execution time	Memory
1204988		ofoz	Bigger segments (IZhO19_segments)	C++17	13 / 100	2 ms	328 KiB

segments

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

#define int long long
#define pi pair<int, int>
#define vi vector<int>
vector<int> a;
vector<int> prfx;

/*
sum(j+1, i) >= a_j
sum(j+1, i) - a_j >= 0
sum(j+1, i) - a_j - sum(0, i) >= -sum(0, i)
-sum(0, j) - a_j >= -sum(0, i)
sum(0, j) + a_j <= sum(0, i)

2 + 2 <= 5
4 <= 5
*/
int getPrfx(int l, int r) {
    int left = (l == 0) ? 0 : prfx[l - 1];
    int right = prfx[r];
    return right - left;
}

bool compare(pi a, pi b) {
    if (a.first > b.first) return true;
    if (a.first < b.first) return false;

    if (a.second < b.second) return true;
    return false;
}

pi findIndex(int i, vi& a, vector<pi>& dp, set<pi> prv) {
    int s1 = getPrfx(0, i);
    auto it = prv.upper_bound({s1, INT64_MAX});
    if (prv.empty() || it == prv.begin()) {
        return {INT32_MIN, -1};
    }
    int j = (--it)->second;
    int s2 = getPrfx(j+1, i);
    pi c = {dp[j+1].first+1, s2};
    return c;
}

signed main() {
    int n;
    cin >> n;

    a.resize(n);
    for (int i = 0; i < n; ++i) cin >> a[i];

    prfx.resize(n);
    prfx[0] = a[0];
    for (int i = 1; i < n; ++i) {
        prfx[i] = prfx[i - 1] + a[i];
    }

    vector<pi> dp(n+1, {-INT64_MAX, INT64_MAX});
    dp[0] = {1, 0};
    int mx = 1;
    set<pi> prv;
    set<pi> prv2;
    for (int i = 0; i < n; i++) {
        int x = a[i];
        pi res = dp[i];
        res.second += x;

        pi c1 = findIndex(i, a, dp, prv);
        pi c2 = findIndex(i, a, dp, prv2);
        if (compare(c1, res)) res = c1;
        if (compare(c2, res)) res = c2;
        dp[i+1] = res;
        if (res.first > mx) {
            mx = res.first;
            prv2 = prv;
            prv.clear();
        }
        int s1 = getPrfx(0, i);
        prv.insert({s1 + res.second, i});


        /*
        for (int j = 0; j < i; j++) {
            pi c = dp[j+1];
            //cerr << j+1 << ' ' << i << ' ' << getPrfx(j, i-1) << endl;
            int s = getPrfx(j+1, i);

            if (s < c.second) continue;
            c.second = s;
            c.first++;
            if (compare(c, res)) res = c;
        }
        */
        
    }

    cout << dp[n].first;
}

• Subtask 1: 13 / 13
• Subtask 2: 0 / 14
• Subtask 3: 0 / 10
• Subtask 4: 0 / 36
• Subtask 5: 0 / 27