Submission #1133827

#	Time	Username	Problem	Language	Result	Execution time	Memory
1133827		lopkus	Bigger segments (IZhO19_segments)	C++20	In queue	0 ms	0 KiB

segments

#include <bits/stdc++.h>

#define int long long

using namespace std;

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    vector<int> a(n + 1);
    for(int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    /*
    for(int i = 1; i <= n; i++) {
        int sum = 0;
        int mx = 0;
        for(int j = i; j >= 1; j--) {
            sum += a[j];
            if(sum >= e[j - 1]) {
                mx = max(mx, dp[j - 1]);
            }
        }
        sum = 0;
        int idx = - 1;
        int mn = 1e18;
        for(int j = i; j >= 1; j--) {
            sum += a[j];
            if(sum >= e[j - 1] && mx == dp[j - 1]) {
                if(mn > sum) {
                    idx = j - 1;
                    mn = min(mn, sum);
                }
            }
        }
        if(idx == - 1) {
            dp[i] = dp[i - 1];
            e[i] = e[i - 1] + a[i];
        }
        else {
            dp[i] = dp[idx] + 1;
            e[i] = mn;
        }
    }*/
    vector<int> dp(n + 1, 0);
    vector<int> e(n + 1, 0);
    e[0] = 0;
    dp[0] = 0;
    vector<int> pref(n + 1, 0);
    for(int i = 1; i <= n; i++) {
        pref[i] = pref[i - 1] + a[i];
    }

    for(int i = 1; i <= n; i++) {
        int p = - 1;
        for(int j = i; j <= n; j++) {
            if(pref[j] - pref[i - 1] >= e[i - 1]) {
                p = j;
                break;
            }
        }
        if(i == 1) {
            dp[i] = 1;
            e[i] = a[1];
        }
        if(a[i] >= e[i - 1]) {
            if(dp[i] < dp[i - 1] + 1) {
                dp[i] = dp[i - 1] + 1;
                e[i] = a[i];
            }
        }
        if(p == - 1) {
            continue;
        }
        for(int j = p; j <= n; j++) {
            if(dp[j] < dp[i - 1] + 1) {
                dp[j] = dp[i - 1] + 1;
                e[j] = pref[j] - pref[i - 1];
            }
            if(dp[j] == dp[i - 1] + 1) {
                e[j] = min(e[j], pref[j] - pref[i - 1]);
            }
        }
    }
    cout << dp[n];
}