Submission #344011

#	Time	Username	Problem	Language	Result	Execution time	Memory
344011		IZhO_2021_I_want_Silver	Bigger segments (IZhO19_segments)	C++14	100 / 100	97 ms	20972 KiB

segments

#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,sse3,sse4,popcnt,abm,mmx")

#include <iostream>
#include <algorithm>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <iomanip>
#include <cassert>
#include <stack>
#include <queue>
#include <deque>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>-

using namespace std;
//using namespace __gnu_pbds;

typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;

// template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
//  order_of_key (k) : Number of items strictly smaller than k .
//  find_by_order(k) : K-th element in a set (counting from zero).
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define pb push_back
#define ppb pop_back
#define mkp make_pair
#define F first
#define S second
#define lb lower_bound
#define ub upper_bound
#define show(a) cerr << #a <<" -> "<< a <<" "
#define nl cerr <<"\n"
#define int ll

const int N = 5e5 + 5;
const int oo = 1e15 + 5;

int n, a[N], sum[N], dp[N], ind[N];

void solve() {
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        cin >> a[i];
        sum[i] = sum[i-1] + a[i];
    }
    ind[1] = 0;
    for (int j = 1; j <= n; ++j) {
        // sum[j] - sum[k] <= sum[i] - sum[j]
        // ind[j] -> k <= j <= bin_search -> i
        // sum[j] + sum[j] - sum[ind[j]]] <= sum[i]
        // ind[i] = max(j, ind[1, 2, ..., i-1])
        ind[j] = max(ind[j-1], ind[j]);
        dp[j] = max(dp[j-1], dp[ind[j]] + 1);
        int l = 1, r = n;
        while (l < r) {
            int mid = (l + r) / 2;
            if (sum[j] + sum[j] - sum[ind[j]] <= sum[mid]) r = mid;
            else l = mid + 1;
        }
        if (sum[j] + sum[j] - sum[ind[j]] <= sum[r]) { ind[r] = j; }
    }
    //for (int i = 1; i <= n; ++i) { show(i); show(ind[i]); nl;}
    cout << dp[n];
}
/*7
5 1 4 5 3 9 9 */
 main () {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	int tests = 1;
	//cin >> tests;
	while (tests --) {
		solve();
	}
	return 0;
}
/*
    Just Chalish!
*/

Compilation message (stderr)

segments.cpp:73:8: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   73 |  main () {
      |        ^

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