Asteroids POJ - 3041(二分圖匹配)
阿新 • • 發佈:2018-10-31
題解:
附上程式碼:
#include<iostream> #include<cstdio> #include<vector> #include<cstring> using namespace std; const int MAX_K=1e4+50; const int MAX_N=5e2+50; const int MAX_V=2*MAX_N; int N,K; int R[MAX_K],C[MAX_K]; vector<int>G[MAX_V]; int match[MAX_V]; bool used[MAX_V]; 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<N;v++){ if(match[v]<0){ memset(used,0,sizeof(used)); if(dfs(v)){ res++; } } } return res; } int main() { scanf("%d%d",&N,&K); for(int i=0;i<K;i++){ scanf("%d%d",&R[i],&C[i]); add_edge(R[i]-1,N+C[i]-1); } printf("%d\n",bipartite_matching()); return 0; }