Submission #937910

#	Time	Username	Problem	Language	Result	Execution time	Memory
937910		kitlix	Dango Maker (JOI18_dango_maker)	C++17	33 / 100	2017 ms	137488 KiB

dango_maker

#include <bits/stdc++.h>

using namespace std;

const int INF = 1e9;

struct Edge {
    int to, f, c, rev;
};

vector<vector<Edge>> g;
vector<int> ptr, dst;

void add_edge(int v, int to) {
    g[v].push_back({to, 0, 1, (int)g[to].size()});
    g[to].push_back({v, 0, 0, (int)g[v].size() - 1});
}

int s, t;

int dfs(int v, int cmin) {
    if (v == t)
        return cmin;
    for (; ptr[v] < (int)g[v].size(); ++ptr[v]) {
        auto& [to, f, c, rev] = g[v][ptr[v]];
        if (c - f < cmin || dst[to] != dst[v] + 1)
            continue;
        int delt = dfs(to, cmin);
        if (delt > 0) {
            f += delt;
            g[to][rev].f -= delt;
            return delt;
        }
    }
    return 0;
}

bool bfs(int cmin) {
    queue<int> q;
    q.push(s);
    dst.assign(g.size(), INF);
    dst[s] = 0;
    while (!q.empty()) {
        int v = q.front();
        q.pop();
        for (auto& [to, f, c, rev] : g[v]) {
            if (c - f < cmin || dst[to] != INF)
                continue;
            dst[to] = dst[v] + 1;
            q.push(to);
        }
    }
    return dst[t] != INF;
}

mt19937 gen(chrono::duration_cast<chrono::milliseconds>(chrono::steady_clock::now().time_since_epoch()).count());

template <typename T>
void shuffle(vector<T>& a) {
    for (int i = 0; i < a.size(); ++i)
        swap(a[i], a[gen() % a.size()]);
}

signed main() {
    ios_base::sync_with_stdio(0), cin.tie(0);
    int n, m;
    cin >> n >> m;
    vector<vector<int>> table(n, vector<int>(m));
    for (auto& r : table) {
        string s;
        cin >> s;
        for (int j = 0; j < m; ++j) {
            if (s[j] == 'R')
                r[j] = 0;
            else if (s[j] == 'G')
                r[j] = 1;
            else
                r[j] = 2;
        }
    }
    g.resize(2 * n * m + 2);
    auto encode = [&](int x, int y) {
        return x * m + y;
        };
    s = 2 * n * m, t = 2 * n * m + 1;
    vector<pair<int, int>> edg_to_add;
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            if (table[i][j] == 0)
                edg_to_add.emplace_back(s, encode(i, j));
            else if (table[i][j] == 1)
                edg_to_add.emplace_back(encode(i, j), n * m + encode(i, j));
            else
                edg_to_add.emplace_back(n * m + encode(i, j), t);
            if (table[i][j])
                continue;
            if (j + 2 < m && table[i][j + 1] == 1 && table[i][j + 2] == 2) {
                edg_to_add.emplace_back(encode(i, j), encode(i, j + 1));
                edg_to_add.emplace_back(n * m + encode(i, j + 1), n * m + encode(i, j + 2));
            }
            if (i + 2 < n && table[i + 1][j] == 1 && table[i + 2][j] == 2) {
                edg_to_add.emplace_back(encode(i, j), encode(i + 1, j));
                edg_to_add.emplace_back(n * m + encode(i + 1, j), n * m + encode(i + 2, j));
            }
        }
    }
    shuffle(edg_to_add);
    for (auto [v, to] : edg_to_add)
        add_edge(v, to);
    int maxflow = 0;
    while (bfs(1)) {
        ptr.assign(g.size(), 0);
        while (int delt = dfs(s, 1)) {
            maxflow += delt;
            ptr.assign(g.size(), 0);
        }
    }
    cout << maxflow;
}

Compilation message (stderr)

dango_maker.cpp: In instantiation of 'void shuffle(std::vector<_Tp>&) [with T = std::pair<int, int>]':
dango_maker.cpp:107:23:   required from here
dango_maker.cpp:60:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   60 |     for (int i = 0; i < a.size(); ++i)
      |                     ~~^~~~~~~~~~

• Subtask 1: 13 / 13
• Subtask 2: 20 / 20
• Subtask 3: 0 / 67