Submission #167367

#	Time	Username	Problem	Language	Result	Execution time	Memory
167367		theboatman	Bigger segments (IZhO19_segments)	C++17	100 / 100	118 ms	25792 KiB

segments

#include <bits/stdc++.h>

#define fi first
#define se second

#define y1 theboatman

using namespace std;
typedef long long ll;

const int N = int(1e6) + 10;
const int inf = int(1e9) + 10;
const long long INF = ll(1e18) + 10;

vector <ll> pref;

ll get(int l, int r) {
    return pref[r] - (l ? pref[l - 1] : 0);
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(0);

    int n;
    cin >> n;

    vector <int> a(n);
    for(int i = 0; i < n; i++) {
        cin >> a[i];
    }

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

    vector <pair <ll, int> > dp(n);
    for(int i = 0; i < n; i++) {
        dp[i] = {get(0, i), 1};
    }

    vector <pair <ll, int> > lazy(n, {INF, inf});

    pair <ll, int> now = {0LL, -1};
    for(int i = 0; i < n; i++) {
        now.fi += a[i];
        now = min(now, lazy[i]);

        dp[i] = min(dp[i], now);
        if (i + 1 == n || get(i + 1, n - 1) < now.fi) {
            continue;
        }

        int l = i + 1, r = n - 1;
        while(l < r) {
            int c = l + r >> 1;

            if (get(i + 1, c) < now.fi) {
                l = c + 1;
            }
            else {
                r = c;
            }
        }

        lazy[l] = min(lazy[l], {get(i + 1, l), now.se - 1});
    }

    cout << -dp[n - 1].se << "\n";
    return 0;
}
/*
*/

Compilation message (stderr)

segments.cpp: In function 'int main()':
segments.cpp:57:23: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
             int c = l + r >> 1;
                     ~~^~~

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