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OI-codes/S2OJ/1891/1891.cpp

180 lines
3.3 KiB
C++

#include <iostream>
#include <algorithm>
#include <queue>
#include <utility>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 2005,
M = 4005;
const int INF = 0x3f3f3f3f;
int n1, n2, n, m, s, t, deg[N << 1];
int idx, head[N << 1], ver[M << 3], edge[M << 3], next[M << 3];
std::pair<int, int> edges[M];
int id[M], dis[N << 1], cur[N << 1];
void add(int u, int v, int w) {
next[idx] = head[u];
ver[idx] = v;
edge[idx] = w;
head[u] = idx++;
}
bool bfs() {
std::fill(std::begin(dis), std::end(dis), 0);
std::queue<int> q;
q.emplace(s);
dis[s] = 1;
cur[s] = head[s];
while (!q.empty()) {
int u = q.front();
q.pop();
for (int i = head[u]; ~i; i = next[i]) {
int v = ver[i],
w = edge[i];
if (w && !dis[v]) {
dis[v] = dis[u] + 1;
cur[v] = head[v];
if (v == t) return true;
q.emplace(v);
}
}
}
return false;
}
int dinic(int u, int limit) {
if (u == t) return limit;
int flow = 0;
for (int i = cur[u]; ~i && flow < limit; i = next[i]) {
cur[u] = i;
int v = ver[i],
w = edge[i];
if (w && dis[v] == dis[u] + 1) {
int k = dinic(v, std::min(w, limit - flow));
if (!k) dis[v] = 0;
edge[i] -= k;
edge[i ^ 1] += k;
flow += k;
}
}
return flow;
}
void solve(int x) {
idx = 0;
std::fill(std::begin(head), std::end(head), -1);
s = 0, t = n + 1;
if (n1 < n2) {
for (int i = 1; i <= n1; i++) {
add(s, i, x);
add(i, s, 0);
}
for (int i = n1 + 1; i <= n; i++) {
add(i, t, x);
add(t, i, 0);
}
for (int i = 1; i <= m; i++) {
int u = edges[i].first,
v = edges[i].second;
id[i] = idx;
add(u, v, 1);
add(v, u, 0);
}
} else {
for (int i = 1; i <= n1; i++) {
add(i, t, x);
add(t, i, 0);
}
for (int i = n1 + 1; i <= n; i++) {
add(s, i, x);
add(i, s, 0);
}
for (int i = 1; i <= m; i++) {
int u = edges[i].first,
v = edges[i].second;
id[i] = idx;
add(v, u, 1);
add(u, v, 0);
}
}
while (bfs()) {
while (dinic(s, INF)) {}
}
for (int i = head[s]; ~i; i = next[i]) {
edge[i] = INF;
}
while (bfs()) {
while (dinic(s, INF)) {}
}
}
int main() {
std::ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n1 >> n2 >> m;
n = n1 + n2;
for (int i = 1, u, v; i <= m; i++) {
cin >> u >> v;
v += n1;
edges[i] = {u, v};
deg[u]++, deg[v]++;
}
int min = *std::min_element(deg + 1, deg + 1 + n);
for (int k = 0; k <= min; k++) {
std::vector<int> used_edges;
solve(k);
for (int i = 1; i <= m; i++) {
if (edge[id[i]] == 0) {
used_edges.emplace_back(i);
}
}
cout << used_edges.size() << ' ';
for (int x : used_edges) {
cout << x << ' ';
}
cout << endl;
}
return 0;
}