Cod sursa(job #2693186)

Utilizator CraniXortDumitrescul Eduard CraniXort Data 5 ianuarie 2021 08:10:02
Problema Flux maxim Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.6 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>

std::ifstream fin("maxflow.in");
std::ofstream fout("maxflow.out");

class Graph{
    private:
        int V, source, sink;
        std::vector <std::vector <int>> edge;
        std::vector <std::vector <int>> cap;
        std::vector <int> parent;
        std::vector <bool> visited;

        bool bfs(){
            std::queue <int> q;
            std::fill(visited.begin(), visited.end(), false);
            visited[source] = true;
            q.push(source);

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

                if(node == sink) continue;

                for(auto& next: edge[node]){
                    if(visited[next] == false and cap[node][next] > 0){
                        visited[next] = true;
                        q.push(next);
                        parent[next] = node;
                    }
                }
            }

            return visited[sink];
        }

    public:
        Graph(int size){
            V = size;
            edge.resize(V+2);
            cap.resize(V+2);
            for(auto& line: cap)
                line.resize(V+2);
            parent.resize(V+2);
            visited.resize(V+2);
        }

        void addEdge(int src, int dest, int capacity, int weight){
            edge[src].push_back(dest);
            edge[dest].push_back(src);
            cap[src][dest] = capacity;
        }

        int maxFlow(int src, int dest){
            source = src;
            sink = dest;

            int maxFlow = 0, flow;
            while(bfs() == true){
                for(int& node: edge[sink]){
                    if(visited[node] == true and cap[node][sink] > 0){
                        parent[sink] = node;
                        flow = 1e9;
                        for(int curr = sink; curr != source; curr = parent[curr])
                            flow = std::min(flow, cap[parent[curr]][curr]);
                        for(int curr = sink; curr != source; curr = parent[curr]){
                            cap[parent[curr]][curr] -= flow;
                            cap[curr][parent[curr]] += flow;
                        }
                        maxFlow += flow;
                    }
                }
            }

            return maxFlow;
        }

};



void readInput(){
    int V, E;
    fin >> V >> E;
    Graph graph(V);
    for(int i=0, src, dest, cap, weight; i<E; i++){
        fin >> src >> dest >> cap;
        graph.addEdge(src, dest, cap, 0);
    }
    fout << graph.maxFlow(1, V);
}

int main(){
    readInput();
    return 0;
}