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shopping.cpp
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shopping.cpp
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//
// shopping.cpp
// Algorithms Lab
//
// Created by Jonas Gessner
// Copyright © 2019 Jonas Gessner. All rights reserved.
//
#include <iostream>
// BGL include #include<boost / graph / adjacency_list.hpp>
#include <boost/graph/adjacency_list.hpp>
// BGL flow include *NEW* #include <boost/graph/push_relabel_max_flow.hpp>
#include <boost/graph/push_relabel_max_flow.hpp>
using namespace std;
typedef boost::adjacency_list_traits<boost::vecS, boost::vecS, boost::directedS> traits;
typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, boost::no_property, boost::property<boost::edge_capacity_t, long, boost::property<boost::edge_residual_capacity_t, long, boost::property<boost::edge_reverse_t, traits::edge_descriptor>>>> graph;
typedef traits::vertex_descriptor vertex_desc;
typedef traits::edge_descriptor edge_desc;
class edge_adder
{
graph &G;
public:
explicit edge_adder(graph &G) : G(G) {}
void add_edge(int from, int to, long capacity)
{
auto c_map = boost::get(boost::edge_capacity, G);
auto r_map = boost::get(boost::edge_reverse, G);
const auto e = boost::add_edge(from, to, G).first;
const auto rev_e = boost::add_edge(to, from, G).first;
c_map[e] = capacity;
c_map[rev_e] = 0; // reverse edge has no capacity!
r_map[e] = rev_e;
r_map[rev_e] = e;
}
};
static void runTestCase()
{
int n, m, s;
cin >> n >> m >> s;
graph G(n);
edge_adder adder(G);
int source = boost::add_vertex(G);
int target = boost::add_vertex(G);
adder.add_edge(0, target, s); // Flow from home to target, allowing the capacity of 1 trip per store.
for (int i = 0; i < s; i++)
{
int storeVertex;
cin >> storeVertex;
adder.add_edge(source, storeVertex, 1); // Flow from source to store with capacity 1, for 1 trip per store (edges can be reused for the to and from trips for 1 store).
}
for (int i = 0; i < m; i++)
{
int u, v;
cin >> u >> v;
// Add an udirected edge with capacity 1
adder.add_edge(u, v, 1);
adder.add_edge(v, u, 1);
}
int flow = boost::push_relabel_max_flow(G, source, target);
if (flow == s)
{
cout << "yes\n";
}
else
{
cout << "no\n";
}
}
int main(int argc, const char *argv[])
{
ios_base::sync_with_stdio(false);
int t;
cin >> t;
for (int i = 0; i < t; i++)
{
runTestCase();
}
return 0;
}