Submission #851037

#	Time	Username	Problem	Language	Result	Execution time	Memory
851037		wakandaaa	Bigger segments (IZhO19_segments)	C++17	100 / 100	55 ms	16068 KiB

segments

#include <bits/stdc++.h>

using namespace std;

#define file ""

#define mp make_pair
#define fi first
#define se second
#define all(x) x.begin(), x.end()

#define getbit(x, i) (((x) >> (i)) & 1)
#define bit(x) (1LL << (x))
#define popcount __builtin_popcountll

mt19937_64 rd(chrono::steady_clock::now().time_since_epoch().count());
int rand(int l, int r) {
    return l + rd() % (r - l + 1);
}

const int N = 1e6 + 5;
const int mod = (int)1e9 + 7; // 998244353;
const int lg = 25; // lg + 1
const int oo = 1e9;
const long long ooo = 1e18;

template<class X, class Y> bool mini(X &a, Y b) {
    return a > b ? (a = b, true) : false;
}
template<class X, class Y> bool maxi(X &a, Y b) {
    return a < b ? (a = b, true) : false;
}
void add(int &a, int b) {
    a += b;
    if (a >= mod) a -= mod;
    if (a < 0) a += mod;
}

int n;
long long a[N];
int f[N], pos[N];

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

    // freopen(file".inp", "r", stdin);
    // freopen(file".out", "w", stdout);

    cin >> n;
    for (int i = 1; i <= n; ++i) {
    	cin >> a[i];
    	a[i] += a[i - 1];
    }

    for (int i = 1; i <= n; ++i) {
    	pos[i] = max(pos[i - 1], pos[i]);
    	f[i] = f[pos[i]] + 1;
    	int l = i, r = n, nxt = 0;
    	while (l <= r) {
    		int mid = (l + r) / 2;
    		if (a[mid] - a[i] >= a[i] - a[pos[i]]) {
    			nxt = mid;
    			r = mid - 1;
    		} else l = mid + 1;
    	}
    	pos[nxt] = i;
    }

    cout << f[n];

    return 0;
}

/*
s[i] - s[j] >= s[j] - s[k] -> binary search
*/

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