Submission #1209330

#	Time	Username	Problem	Language	Result	Execution time	Memory
1209330		SpyrosAliv	Nafta (COI15_nafta)	C++20	100 / 100	332 ms	110152 KiB

nafta

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

vector<pair<int, int>> delta = {{-1, 0}, {1, 0}, {0, 1}, {0, -1}};
const int MN = 2001;
int grid[MN][MN], c[MN][MN], dp[MN][MN], fin[MN], tot[MN], n, m, lb, rb, s;
bool vis[MN][MN];
vector<vector<pair<int, int>>> rr(MN);

bool inside(int i, int j) {
    return i >= 1 && i <= n && j >= 1 && j <= m;
}

void flood(int i, int j) {
    s += grid[i][j];
    vis[i][j] = true;
    lb = min(lb, j);
    rb = max(rb, j);
    for (auto [pi, pj]: delta) {
        int ni = i + pi;
        int nj = j + pj;
        if (inside(ni, nj) && grid[ni][nj] != -1 && !vis[ni][nj]) {
            flood(ni, nj);
        }
    }
}

void dnc(int l, int r, int optl, int optr, int k) {
    if (l > r) return;
    int mid = (l + r) >> 1;
    int best = -1, opt = -1;
    for (int i = optl; i <= min(optr, mid); i++) {
        int ans = c[i][mid];
        if (i > 1 && k > 1) ans += dp[i-1][k-1];
        if (ans > best) {
            best = ans;
            opt = i;
        }
    }   
    dp[mid][k] = best;
    fin[k] = max(fin[k], best);
    dnc(l, mid - 1, optl, opt, k);
    dnc(mid+1, r, opt, optr, k);
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= m; j++) {
            char c; cin >> c;
            if (c == '.') {
                grid[i][j] = -1;
            }
            else grid[i][j] = (c - '0');
        }
    }
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= m; j++) {
            if (vis[i][j] || grid[i][j] == -1) continue;
            s = 0;
            lb = j;
            rb = j;
            flood(i, j);
            tot[lb] += s;
            rr[rb].push_back({lb, s});
        }
    }
    swap(n, m);
    for (int i = 1; i <= n; i++) {
        for (int j = i; j >= 1; j--) {
            if (i == j) c[j][i] = tot[i];
            else c[j][i] = c[j+1][i] + tot[j];
        }
        for (auto [ll, ss]: rr[i]) {
            tot[ll] -= ss;
        }
    }
    for (int k = 1; k <= n; k++) {
        dnc(1, n, 1, n, k);
        cout << fin[k] << "\n";
    }
    return 0; 
}

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