FLOW1 - Giao lưu
Tác giả: ladpro98
Ngôn ngữ: C++
#include <bits/stdc++.h>
const int N = 1111;
const int INF = int(1e9);
using namespace std;
int n, nProblem;
int contestant(int side, int id) {
return n * side + id;
}
int problem(bool out, int id) {
return n + n + nProblem * out + id;
}
struct edge {
int u, v;
int cap, flow;
edge(int _u, int _v, int _c) {
u = _u; v = _v; cap = _c;
flow = 0;
}
};
struct network {
int n;
int source, sink;
int maxFlow;
int T[N];
vector<int> a[N];
vector<edge> E;
void addEdge(int u, int v, int c) {
a[u].push_back(E.size()); //* forward
a[v].push_back(E.size() + 1); //* reverse
E.push_back(edge(u, v, c));
E.push_back(edge(v, u, 0)); //* directed graph
}
bool findPath() {
queue<int> Q;
Q.push(source);
for (int i = 1; i <= n; ++i)
T[i] = 0;
while (!Q.empty()) {
int u = Q.front(); Q.pop();
for (int id: a[u]) {
int v = E[id].v;
if (T[v] == 0 && E[id].cap > E[id].flow) {
T[v] = id;
if (v == sink) return 1;
Q.push(v);
}
}
}
return 0;
}
void incFlow() {
int delta = INF;
for (int v = sink, u = T[v]; v != source; v = E[u].u, u = T[v])
delta = min(delta, E[u].cap - E[u].flow);
for (int v = sink, u = T[v]; v != source; v = E[u].u, u = T[v])
E[u].flow += delta, E[u ^ 1].flow -= delta;
maxFlow += delta;
}
void edmondsKarp() {
while (findPath()) incFlow();
}
int getFlow(int u, int v) {
for (int id: a[u])
if (E[id].v == v)
return E[id].flow;
return 0;
}
} G;
int main() {
ios::sync_with_stdio(0); cin.tie(0);
#ifdef _LAD_
freopen("FLOW1.txt", "r", stdin);
#endif // _LAD_
cin >> n >> nProblem;
G.source = n + n + nProblem + nProblem + 1;
G.sink = G.n = G.source + 1; //* number of vertexes equals sink
string line;
getline(cin, line);
for (int side = 0; side <= 1; ++side) {
for (int i = 1; i <= n; ++i) {
getline(cin, line);
istringstream input(line);
int prob;
while (input >> prob) {
if (side == 0)
G.addEdge(contestant(side, i), problem(0, prob), 1);
else
G.addEdge(problem(1, prob), contestant(side, i), 1);
}
}
}
for (int i = 1; i <= n; ++i)
G.addEdge(G.source, contestant(0, i), 1);
for (int i = 1; i <= n; ++i)
G.addEdge(contestant(1, i), G.sink, 1);
for (int i = 1; i <= nProblem; ++i)
G.addEdge(problem(0, i), problem(1, i), 1);
G.edmondsKarp();
for (int i = 1; i <= nProblem; ++i) {
if (G.getFlow(problem(0, i), problem(1, i))) {
for (int id: G.a[problem(0, i)])
if (G.E[id].v <= n && G.E[id].flow) {
cout << G.E[id].v << ' ';
break;
}
for (int id: G.a[problem(1, i)])
if (n < G.E[id].v && G.E[id].v <= n + n && G.E[id].flow) {
cout << G.E[id].v - n << endl;
break;
}
} else {
cout << 0 << ' ' << 0 << endl;
}
}
return 0;
}