Submission #1282160

#	Time	Username	Problem	Language	Result	Execution time	Memory
1282160		wedonttalkanymore	Nafta (COI15_nafta)	C++20	34 / 100	290 ms	79232 KiB

nafta

#include <bits/stdc++.h>
using namespace std;
using ll = long long;

#define int long long
#define pii pair<ll, ll>
#define fi first
#define se second

const ll N = 4e3 + 5, inf = 1e18, mod = 1e9 + 7, block = 320, lim = 19;
const long long NEG = -(1LL<<60);

int m, n;
char a[N][N];
int dx[] = {-1, 0, 1, 0};
int dy[] = {0, 1, 0, -1};
struct item {
    int L, R, sum;
};
item pre[N];
int minn = inf, maxx = 0, sum = 0;
bool vst[N][N];
int cost[N][N];
int dp[N][N];

void bfs(int stx, int sty) {
    vst[stx][sty] = 1;
    queue<pii> q;
    q.push({stx, sty});
    sum += a[stx][sty] - '0';
    minn = min(minn, sty);
    maxx = max(maxx, sty);
    while(q.size()) {
        auto [x, y] = q.front();
        q.pop();
        for (int i = 0; i < 4; i++) {
            int nx = x + dx[i], ny = y + dy[i];
            if (nx < 1 || ny < 1 || nx > m || ny > n) continue;
            if (a[nx][ny] == '.' || vst[nx][ny]) continue;
            vst[nx][ny] = 1;
            sum += a[nx][ny] - '0';
            minn = min(minn, ny);
            maxx = max(maxx, ny);
            q.push({nx, ny});
        }
    }
}

bool cmp(item a, item b) {
    return a.L < b.L;
}

struct Fenwick {
    vector<int> bit;
    int sz;
    Fenwick (int _n) {
        bit.assign(_n + 5, 0);
        sz = _n;
    }
    void update(int i, int val) {
        if (i <= 0) return;
        while(i <= sz) {
            bit[i] += val;
            i += i & -i;
        }
    }
    int get(int i) {
        if (i == 0) return 0;
        int res = 0;
        while(i > 0) {
            res += bit[i];
            i -= i & -i;
        }
        return res;
    }
    int get(int l, int r) {
        if (l > r) return 0;
        return get(r) - get(l - 1);
    }
} fw(N);

void dnc(int k, int l, int r, int L, int R) {
    if (l > r) return;
    int mid = (l + r) / 2;
    int Left = max(0LL, L);
    int Right = min(mid - 1, R);
    long long best = NEG;
    int pos = Left;
    if (Left <= Right) {
        for (int j = Left; j <= Right; j++) {
            long long cur = dp[k - 1][j] + cost[mid][j];
            if (cur > best) {
                best = cur;
                pos = j;
            }
        }
    } else {
        best = NEG;
        pos = Left;
    }
    dp[k][mid] = best;
    dnc(k, l, mid - 1, L, pos);
    dnc(k, mid + 1, r, pos, R);
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    if (fopen(".inp", "r")) {
        freopen(".inp", "r", stdin);
        freopen(".out", "w", stdout);
    }
    cin >> m >> n;
    for (int i = 1; i <= m; i++) {
        for (int j = 1; j <= n; j++) {
            cin >> a[i][j];
        }
    }
    int tt = 0;
    for (int i = 1; i <= m; i++) {
        for (int j = 1; j <= n; j++) {
            if (a[i][j] != '.' && !vst[i][j]) {
                minn = inf, maxx = 0, sum = 0;
                bfs(i, j);
                pre[++tt] = {minn, maxx, sum};
            }
        }
    }
    sort(pre + 1, pre + tt + 1, cmp);
    priority_queue<pii, vector<pii>, greater<pii>> q;
    int l = 1;
    for (int i = 1; i <= n; i++) {
        while(q.size() && q.top().fi < i) {
            int id = q.top().se;
            int L = pre[id].L, s = pre[id].sum;
            fw.update(L, -s);
            q.pop();
        }
        while(l <= tt && pre[l].L <= i) {
            fw.update(pre[l].L, pre[l].sum);
            q.push({pre[l].R, l});
            l++;
        }
        for (int j = 0; j < i; j++) {
            int val = fw.get(j + 1, i);
            cost[i][j] = val;
        }
    }
    for (int j = 0; j <= n; j++) dp[0][j] = NEG;
    dp[0][0] = 0;
    for (int k = 1; k <= n; k++) {
        for (int i = 1; i <= n; i++) dp[k][i] = NEG;
        dnc(k, 1, n, 0, n - 1);
    }
    for (int k = 1; k <= n; k++) {
        int val = *max_element(dp[k] + 1, dp[k] + n + 1);
        cout << val << '\n';
    }
    return 0;
}

Compilation message (stderr)

nafta.cpp: In function 'int main()':
nafta.cpp:110:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  110 |         freopen(".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~
nafta.cpp:111:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  111 |         freopen(".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 23 / 23
• Subtask 3: 0 / 66