Submission #1007331

#	Time	Username	Problem	Language	Result	Execution time	Memory
1007331		VMaksimoski008	Nafta (COI15_nafta)	C++17	100 / 100	365 ms	130892 KiB

nafta

#include <bits/stdc++.h>
using namespace std;
using Comp = array<int, 3>;

struct BIT {
    int n;
    vector<int> tree;

    BIT(int _n) : n(_n+60), tree(_n+60) {}

    void update(int p, int v) {
        for(p++; p<n; p+=p&-p) tree[p] += v;
    }

    int query(int p) {
        int ans = 0;
        for(p++; p>0; p-=p&-p) ans += tree[p];
        return ans;
    }

    int query(int l, int r) { return query(r) - query(l-1); }
};

int dr[4] = {0, -1, 0, 1}, dc[4] = {-1, 0, 1, 0};
char M[2005][2005];
int L=1e9, R=-1, sum=0, n, m, dp[2005][2005], val[2005][2005], vis[2005][2005];
vector<Comp> comp;

void dfs(int r, int c) {
    vis[r][c] = 1;
    L = min(L, c); R = max(R, c);
    sum += (M[r][c] - '0');

    for(int i=0; i<4; i++) {
        int nr = r + dr[i], nc = c + dc[i];
        if(nr < 0 || nr >= n || nc < 0 || nc >= m) continue;
        if(vis[nr][nc] || M[nr][nc] == '.') continue;
        dfs(nr, nc);
    }
}

void f(int l, int r, int tl, int tr, int j) {
    if(l > r) return ;
    int tm = (l + r) / 2, p = tl;

    for(int i=tl; i<=min(tm, tr); i++) {
        int v = dp[i-1][j-1] + val[i][tm];
        if(v > dp[tm][j]) {
            dp[tm][j] = v;
            p = i;
        }
    }

    f(l, tm-1, tl, p, j);
    f(tm+1, r, p, tr, j);
}

signed main() {
    cin >> n >> m;
    for(int i=0; i<n; i++)
        for(int j=0; j<m; j++) cin >> M[i][j];

    for(int i=0; i<n; i++) {
        for(int j=0; j<m; j++) {
            if(vis[i][j] || M[i][j] == '.') continue;
            L=1e9, R=-1, sum=0;
            dfs(i, j);
            comp.push_back({ L+1, R+1, sum });
        }
    }

    sort(comp.begin(), comp.end(), [&](Comp &a, Comp &b) { return a[1] < b[1]; });

    BIT bit(m);
    for(auto &[l, r, v] : comp) bit.update(l, v);

    int ptr = 0;
    for(int j=1; j<=m; j++) {
        while(ptr < comp.size() && comp[ptr][1] < j) {
            bit.update(comp[ptr][0], -comp[ptr][2]);
            ptr++;
        }

        for(int i=1; i<=j; i++) val[i][j] = bit.query(i, j);
    }
    
    for(int i=1; i<=m; i++) {
        f(1, m, 1, m, i);
        int mx = 0;
        for(int j=1; j<=m; j++) mx = max(mx, dp[j][i]);
        cout << mx << '\n';
    }
    return 0;
}

Compilation message (stderr)

nafta.cpp: In function 'int main()':
nafta.cpp:79:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::array<int, 3> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   79 |         while(ptr < comp.size() && comp[ptr][1] < j) {
      |               ~~~~^~~~~~~~~~~~~

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