Cod sursa(job #2750075)

Utilizator flibiaVisanu Cristian flibia Data 9 mai 2021 20:32:05
Problema Flux maxim Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 6.23 kb
// g++ -std=c++17 -DLOCAL a.cpp -o ex && ./ex >tst.out 2>&1
#include <bits/stdc++.h>

using namespace std;

template <typename A, typename B>
string to_string(pair<A, B> p);
 
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p);
 
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p);
 
string to_string(const string& s) {
    return '"' + s + '"';
}
 
string to_string(const char* s) {
    return to_string((string) s);
}
 
string to_string(bool b) {
    return (b ? "true" : "false");
}
 
string to_string(vector<bool> v) {
    bool first = true;
    string res = "{";
    for (int i = 0; i < static_cast<int>(v.size()); i++) {
        if (!first) {
            res += ", ";
        }
        first = false;
        res += to_string(v[i]);
    }
    res += "}";
    return res;
}
 
template <size_t N>
string to_string(bitset<N> v) {
    string res = "";
    for (size_t i = 0; i < N; i++) {
        res += static_cast<char>('0' + v[i]);
    }
    return res;
}
 
template <typename A>
string to_string(A v) {
    bool first = true;
    string res = "{";
    for (const auto &x : v) {
        if (!first) {
            res += ", ";
        }
        first = false;
        res += to_string(x);
    }
    res += "}";
    return res;
}
 
template <typename A, typename B>
string to_string(pair<A, B> p) {
    return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
 
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p) {
    return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ")";
}
 
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p) {
    return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}
 
void debug_out() { cerr << "   "; }
void debug_out_nl() { cerr << endl; }
 
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << " " << to_string(H);
    debug_out(T...);
}

template <typename Head, typename... Tail>
void debug_out_nl(Head H, Tail... T) {
    cerr << " " << to_string(H);
    debug_out_nl(T...);
}
 
#ifdef LOCAL
#define dbg(...) cerr << "#" << #__VA_ARGS__ << ":", debug_out(__VA_ARGS__)
#define nl(...) cerr << "#" << #__VA_ARGS__ << ":", debug_out_nl(__VA_ARGS__)
#else
#define dbg(...) 69
#define nl(...) 42
#endif

#define ll long long
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
ll random(ll st, ll dr) {
    assert(st <= dr);
    return st + rng() % (dr - st + 1);
}

template<typename T>
struct Edge {
    int from;
    int to;
    T cap;
    T flow;

    Edge(int _from, int _to, T _cap) : from(_from), to(_to), cap(_cap), flow(0) {}

    T resCap() {
        return cap - flow; // residual capacity
    }
};

template<typename T>
struct Dinic {
    static const T INF = INT_MAX; // Change
    bool isDirected;
    int source;
    int sink;
    vector<Edge<T>> edges;
    vector<vector<int> > v;
    vector<int> level;
    vector<int> lst;
    int N;
    int M;
    T computedMaxFlow; 
    bool isComputed;

    Dinic(bool _isDirected, int _source, int _sink, int _N) : isDirected(_isDirected), source(_source), sink(_sink), v(_N), level(_N), lst(_N), N(_N), M(0), isComputed(false) {}

    void addEdge(int from, int to, T cap) {
        /*
            Pentru o muchie intre x, y, c apelam o singura data addEdge(x, y, c)
        */
        edges.push_back(Edge<T>(from, to, cap));
        edges.push_back(Edge<T>(to, from, (isDirected ? 0 : cap)));
        v[from].push_back(M++);
        v[to].push_back(M++);
    }

    bool canPush() {
        queue<int> q;
        fill(level.begin(), level.end(), -1);

        level[source] = 0;
        q.push(source);

        while (!q.empty()) {
            int node = q.front();
            q.pop();

            if (node == sink) {
                return true;
            }

            for (auto edgeId : v[node]) {
                int nxt = edges[edgeId].to;

                if (level[nxt] == -1) {
                    if (edges[edgeId].resCap() > 0) {
                        level[nxt] = level[node] + 1;
                        q.push(nxt);
                    }
                }
            }
        }

        return false;
    }

    T push(int node, T pushedFlow) {
        if (pushedFlow == 0) {
            return 0;
        }

        if (node == sink) {
            return pushedFlow;
        }

        for (; lst[node] < v[node].size(); lst[node]++) {
            int edgeId = v[node][lst[node]];
            int nxt = edges[edgeId].to;
            T resCap = edges[edgeId].resCap();

            if (level[nxt] != level[node] + 1 || resCap <= 0) {
                continue;
            }

            T flow = push(nxt, min(pushedFlow, resCap));
            if (flow == 0) {
                continue;
            }

            edges[edgeId].flow += flow;
            edges[edgeId ^ 1].flow -= flow;

            return flow;
        }

        return 0;
    }

    T maxFlow() {
        if (isComputed) {
            return computedMaxFlow;
        }

        T flow = 0;
        while (canPush()) {
            fill(lst.begin(), lst.end(), 0);

            while (1) {
                T pushedFlow = push(source, INF);
                if (pushedFlow <= 0) {
                    break;
                }

                flow += pushedFlow;
            }
        }

        isComputed = true;
        computedMaxFlow = flow;
        
        return computedMaxFlow;
    }
};

const int MOD = 1e9 + 7;
const int N = 2e5 + 10;

void solve(int test, istream &cin, ostream &cout) {
    int n, m;
    cin >> n >> m;
    
    Dinic<int> graph(true, 1, n, n + 1);
    
    for (int i = 1, x, y, c; i <= m; i++) {
        cin >> x >> y >> c;
        graph.addEdge(x, y, c);
    }

    cout << graph.maxFlow();

    // cerr << "Time elapsed :" << clock() * 1000.0 / CLOCKS_PER_SEC << " ms" << '\n';
}

int main() {
    ifstream cin("maxflow.in");
    ofstream cout("maxflow.out");
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);

    bool multiTest = false;

    int t;    
    if (multiTest) {
        cin >> t;
    } else {
        t = 1;
    }

    for (int test = 1; test <= t; test++) {
        solve(test, cin, cout);
    }

    return 0;
}