Submission #989092

#	Time	Username	Problem	Language	Result	Execution time	Memory
989092		armashka	Bigger segments (IZhO19_segments)	C++17	37 / 100	180 ms	141660 KiB

segments

#include<bits/stdc++.h>

#pragma GCC target("avx2")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

using namespace std;

#define fast ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define file(s) freopen(s".in", "r", stdin);freopen(s".out", "w", stdout);
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
#define pb push_back
#define pf push_front
#define ppb pop_back
#define ft first
#define sd second
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
const int N = 1e6 + 10;
const int M = 2e7 + 5;
const int B = 316;
const ll msize = 2;
const ll mod1 = 1e9 + 7;
const ll mod2 = 998244353;
const long double Phi = acos(-1);
const long long inf = 2e18;
const vector <pair<int, int>> dir = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};

ll binmul(ll x, ll ti, ll m);
ll binpow(ll x, ll ti, ll m);

ll n, a[3005], dp[3005][3005], pref[3005], suf[3005][3005];

const void solve() {
    cin >> n;
    for (int i = 1; i <= n; ++ i) cin >> a[i], pref[i] = pref[i - 1] + a[i];

    for (int i = 0; i <= n; ++ i) {
        for (int j = 0; j <= n; ++ j) {
            dp[i][j] = suf[i][j] = -inf;
        }
    }

    for (int i = 1; i <= n; ++ i) dp[1][i] = 1;

    suf[1][1] = 1;

    for (int i = 2; i <= n; ++ i) {
        for (int j = i; j >= 1; -- j) {
            // for (int k = j - 1; k >= 1; -- k) {
            //     ll sum1 = pref[i] - pref[j - 1];
            //     ll sum2 = pref[j - 1] - pref[k - 1];

            //     if (sum2 <= sum1) {
            //         dp[j][i] = max(dp[j][i], dp[k][j - 1] + 1);
            //     }
            // }  

            int l = 1, r = j - 1, k = -1;
            while (l <= r) {
                int mid = (l + r) / 2;
                if (pref[j - 1] - pref[mid - 1] <= pref[i] - pref[j - 1]) r = mid - 1, k = mid;
                else l = mid + 1;
            }

            if (k != -1) dp[j][i] = max(dp[j][i], suf[k][j - 1] + 1);
        }
        suf[i][i] = dp[i][i];
        for (int j = i - 1; j >= 1; -- j) 
            suf[j][i] = max(dp[j][i], suf[j + 1][i]);
    }

    ll ans = 0;
    for (int i = 1; i <= n; ++ i) ans = max(ans, dp[i][n]);
    cout << ans;
}  
                                  
int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    srand(time(NULL));

    // file("maze");

    // freopen("input.txt", "r", stdin);
    // freopen("output.txt", "w", stdout);

    int tt = 1;
    // cin >> tt;
    for (int i = 1; i <= tt; ++ i) {
        solve();
    }

    #ifndef ONLINE_JUDGE
    cerr << "\n" << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
    #endif

    return 0;
} 


// Template functions
ll binmul(ll x, ll ti, ll m) { ll res = 0;while (ti){if(ti & 1)res += x;x += x;ti >>= 1; x %= m; res %= m;} return res;}
ll binpow(ll x, ll ti, ll m) { ll res = 1;while (ti){if(ti & 1)(res *= x)%=m;(x*=x)%=m;ti >>= 1; x %= m; res %= m;} return res;}

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