Submission #739584

#	Time	Username	Problem	Language	Result	Execution time	Memory
739584		stevancv	The short shank; Redemption (BOI21_prison)	C++14	45 / 100	1472 ms	258012 KiB

prison

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 4000 + 2;
const int inf = 1e9;
int st[4 * N], lzy[4 * N];
void Propagate(int node, int l, int r) {
    if (lzy[node] == 0) return;
    if (l < r) {
        lzy[2 * node] += lzy[node];
        lzy[2 * node + 1] += lzy[node];
    }
    st[node] += lzy[node];
    lzy[node] = 0;
}
void Add(int node, int l, int r, int ql, int qr, int x) {
    Propagate(node, l, r);
    if (r < ql || qr < l) return;
    if (ql <= l && r <= qr) {
        lzy[node] += x;
        Propagate(node, l, r);
        return;
    }
    int mid = l + r >> 1;
    Add(2 * node, l, mid, ql, qr, x);
    Add(2 * node + 1, mid + 1, r, ql, qr, x);
    st[node] = max(st[2 * node], st[2 * node + 1]);
}
int Get(int node, int l, int r, int ql, int qr) {
    Propagate(node, l, r);
    if (r < ql || qr < l) return 0;
    if (ql <= l && r <= qr) return st[node];
    int mid = l + r >> 1;
    return max(Get(2 * node, l, mid, ql, qr), Get(2 * node + 1, mid + 1, r, ql, qr));
}
void Dodaj(int l, int r, int o) {
    Add(1, 0, N, l, r, o);
}
int cost[N][N], rmx[N][N];
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n, d, t;
    cin >> n >> d >> t;
    vector<int> a(n);
    for (int i = 0; i < n; i++) cin >> a[i];
    stack<int> s;
    vector<int> gr(n, inf);
    int ans = 0;
    for (int i = 0; i < n; i++) {
        if (a[i] > t) {
            while (!s.empty() && a[s.top()] - s.top() + i > t) s.pop();
            if (!s.empty()) {
                gr[i] = s.top();
                ans += 1;
            }
        }
        s.push(i);
    }
    for (int i = 0; i < n; i++) if (a[i] <= t) ans++;
    vector<array<int, 2>> svi;
    for (int i = 0; i < n; i++) {
        if (gr[i] != inf) svi.push_back({gr[i] + 1, i});
    }
    if (d == 1) {
        vector<int> su(n);
        for (int i = 0; i < svi.size(); i++) {
            su[svi[i][0]] += 1;
            su[svi[i][1] + 1] -= 1;
        }
        int mx = 0;
        for (int i = 0; i < n; i++) {
            if (i > 0) su[i] += su[i - 1];
            smax(mx, su[i]);
        }
        cout << ans - mx << en;
        return 0;
    }
    sort(svi.begin(), svi.end());
    n = svi.size();
    for (int i = 0; i < n; i++) {
        int y = 0;
        for (int j = i; j < n; j++) {
            smax(y, svi[j][1]);
            rmx[i][j] = y;
        }
    }
    for (int i = 0; i < n; i++) {
        if (i % 2 == 0) {
            for (int j = i; j < n; j++) {
                Dodaj(svi[j][0], svi[j][1], 1);
                cost[i][j] = Get(1, 0, N, svi[i][0], rmx[i][j]);
            }
        }
        else {
            Dodaj(svi[i - 1][0], svi[i - 1][1], -1);
            for (int j = n - 1; j >= i; j--) {
                cost[i][j] = Get(1, 0, N, svi[i][0], rmx[i][j]);
                Dodaj(svi[j][0], svi[j][1], -1);
            }
        }
    }

    /*for (int i = 0; i < n; i++) {
        int y = 0;
        for (int j = i; j < n; j++) {
            Dodaj(svi[j][0], svi[j][1], 1);
            smax(y, svi[j][1]);
            cost[i][j] = Get(1, 0, N, svi[i][0], y);
        }
        for (int j = i; j < n; j++) Dodaj(svi[j][0], svi[j][1], -1);
    }*/
    vector<int> dp(n);
    while (d--) {
        vector<int> ndp(n);
        function<void(int, int, int, int)> Solve = [&] (int l, int r, int opl, int opr) {
            if (l > r) return;
            int best = 0;
            int mid = l + r >> 1;
            for (int j = opl; j <= min(opr, mid); j++) {
                int x = cost[j][mid];
                if (j > 0) x += dp[j - 1];
                if (x >= ndp[mid]) {
                    ndp[mid] = x;
                    best = j;
                }
            }
            Solve(l, mid - 1, opl, best);
            Solve(mid + 1, r, best, opr);
        };
        Solve(0, n - 1, 0, n - 1);
        swap(dp, ndp);
    }
    cout << ans - dp.back() << en;
    return 0;
}

Compilation message (stderr)

prison.cpp: In function 'void Add(int, int, int, int, int, int)':
prison.cpp:29:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   29 |     int mid = l + r >> 1;
      |               ~~^~~
prison.cpp: In function 'int Get(int, int, int, int, int)':
prison.cpp:38:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   38 |     int mid = l + r >> 1;
      |               ~~^~~
prison.cpp: In function 'int main()':
prison.cpp:73:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::array<int, 2> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   73 |         for (int i = 0; i < svi.size(); i++) {
      |                         ~~^~~~~~~~~~~~
prison.cpp: In lambda function:
prison.cpp:125:25: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  125 |             int mid = l + r >> 1;
      |                       ~~^~~

• Subtask 1: 15 / 15
• Subtask 2: 10 / 10
• Subtask 3: 20 / 20
• Subtask 4: 0 / 10
• Subtask 5: 0 / 25
• Subtask 6: 0 / 20