Submission #407425

#	Time	Username	Problem	Language	Result	Execution time	Memory
407425		534351	Cigle (COI21_cigle)	C++17	48 / 100	1097 ms	64200 KiB

cigle

#include <bits/stdc++.h>

using namespace std;

template<class T, class U>
void ckmin(T &a, U b)
{
    if (a > b) a = b;
}

template<class T, class U>
void ckmax(T &a, U b)
{
    if (a < b) a = b;
}

#define MP make_pair
#define PB push_back
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
#define FOR(i, a, b) for (auto i = (a); i < (b); i++)
#define FORD(i, a, b) for (auto i = (a) - 1; i >= (b); i--)
#define SZ(x) ((int) (x).size())
#define ALL(x) (x).begin(), (x).end()

const int MAXN = 5013;

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<pii> vpi;
typedef vector<pll> vpl;

int N;
int arr[MAXN], pref[MAXN];
int dp[MAXN][MAXN];
int ans;
int seg[4 * MAXN], lazy[4 * MAXN];

void build(int w, int L, int R, int k)
{
    lazy[w] = 0;
    if (L == R)
    {
        seg[w] = dp[L][k];
        return;
    }
    int mid = (L + R) >> 1;;
    build(w << 1, L, mid, k);
    build(w << 1 | 1, mid + 1, R, k);
    seg[w] = max(seg[w << 1], seg[w << 1 | 1]);
}
void push(int w, int L, int R)
{
    if (!lazy[w]) return;
    seg[w] += lazy[w];
    if (L != R)
    {
        lazy[w << 1] += lazy[w];
        lazy[w << 1 | 1] += lazy[w];
    }
    lazy[w] = 0;
    return;
}
void update(int w, int L, int R, int a, int b)
{
    push(w, L, R);
    if (b < L || R < a)
    {
        return;
    }
    if (a <= L && R <= b)
    {
        lazy[w]++;
        push(w, L, R);
        return;
    }
    int mid = (L + R) >> 1;
    update(w << 1, L, mid, a, b);
    update(w << 1 | 1, mid + 1, R, a, b);
    seg[w] = max(seg[w << 1], seg[w << 1 | 1]);
}

int32_t main()
{
    ios_base::sync_with_stdio(false); cin.tie(0);
    cout << fixed << setprecision(12);
    cerr << fixed << setprecision(4);
    cin >> N;
    FOR(i, 0, N)
    {
        cin >> arr[i];
        pref[i + 1] = pref[i] + arr[i];
    }
    // dp[0][0] = 0;
    FOR(i, 1, N + 1)
    {
        int iter = i - 1;
        FOR(j, i, N + 1)
        {
            // dp[i][j] = 0;
            // FOR(k, 1, i)
            // {
            //     ckmax(dp[i][j], dp[k][i - 1]);
            // }
            dp[i][j] = seg[1];
            int c = 2 * pref[i - 1] - pref[j];
            while(iter != 0 && pref[iter] > c)
            {
                iter--;
            }
            // cerr << "dp " << i << ' ' << j << " = " << dp[i][j] << endl;
            if (pref[iter] == c)
            {
                // FOR(k, 1, iter + 1)
                // {
                //     // cerr << "ADD " << k << ' ' << i - 1 << endl;
                //     dp[k][i - 1]++;
                // }
                update(1, 1, i - 1, 1, iter);
            }
            //i...j. that means you use i-1....j-1.
            //count how many s i-2...k = si-1...c
            //pref[i-1] - pref[k] = pref[j] - pref[i - 1].
            //pref[k] = 2 pref[i - 1] - pref[j]
            //find dp[i][j].
            //dp[i][j] = max(dp[i][j], dp[k][i - 1] + c(k, i, j))
            //c(k, i, j) is # of positions l such that s[k] +
            //there's always some poition
        }
        build(1, 1, i, i);
    }
    FOR(i, 1, N + 1)
    {
        ckmax(ans, dp[i][N]);
    }
    cout << ans << '\n';
    return 0;
}

• Subtask 1: 9 / 9
• Subtask 2: 11 / 11
• Subtask 3: 13 / 13
• Subtask 4: 15 / 15
• Subtask 5: 0 / 52