poj 3041

二分图匹配

#include <iostream>#include <vector>#include <cstring>using namespace std;const int MAX_N = 505;const int MAX_K = 10005;int n, k, V;int r[MAX_K], c[MAX_K];int match[MAX_K];bool used[MAX_K];vector<int> G[MAX_K];void add_edge(int u, int v) {G[u].push_back(v);G[v].push_back(u);}bool dfs(int v) {used[v] = true;for(int i=0; i<G[v].size(); i++) {int u = G[v][i], w = match[u];if(w<0 || !used[w] && dfs(w)) {match[v] = u;match[u] = v;return true;}}return false;}int bipartite_matching() {int res = 0;memset(match, -1, sizeof(match));for(int v=0; v<V; v++) {if(match[v] < 0) {memset(used, 0, sizeof(used));if(dfs(v))res++;}}return res;}void solve() {V = 2 * n;for(int i=0; i<k; i++)add_edge(r[i]-1, n+c[i]-1);printf("%d\n", bipartite_matching());}int main() {scanf("%d%d", &n, &k);for(int i=0; i<k; i++)scanf("%d%d", &r[i], &c[i]);solve();return 0;}