[Loj]#6002. 「网络流 24 题」最小路径覆盖

题意如题名，最小路径覆盖。

答案为点数减去最大匹配。

用匈牙利直接跑。

#include <cstdio>#include <cstring>#include <vector>using namespace std;const int N=205;int n,m;int map[N][N];int fr[N];int vis[N];int sum;int in[N];int le;int fa[N];vector <int > path[N];int get(int x){return x==fa[x]?x:fa[x]=get(fa[x]);}void me(int x,int y){int fx=get(x),fy=get(y);fa[fx]=fy;}bool find(int x){for (int i=1;i<=n;i++){if (map[x][i]&&!vis[i]){vis[i]=1;if (!fr[i]||find(fr[i])) {fr[i]=x;return 1;}}}return 0;}int main(){register int i,j;scanf("%d %d",&n,&m);for (i=1;i<=m;i++){int x,y;scanf("%d %d",&x,&y);map[x][y]=1;}for (i=1;i<=n;i++){memset(vis,0,sizeof(vis));if (find(i)) sum++;}//memset(vis,0,sizeof(vis));for (i=1;i<=n;i++) fa[i]=i;for (i=1;i<=n;i++){if (fr[i])if (fa[i]!=fa[fr[i]]) me(i,fr[i]);}for (i=1;i<=n;i++){path[fa[i]].push_back(i);}for (i=1;i<=n;i++){if (path[i].size()){for (j=0;j<path[i].size();j++){printf("%d ",path[i][j]);}printf("\n");}}printf("%d",n-sum);}