Templates - bipartite graph matching KM

The specific method is not introduced, see https://blog.csdn.net/sixdaycoder/article/details/47720471

The main point about some attention:

1: slack open out to save time, because with a non-stop cycle x slack will continue to shrink, to be updated

2: Because multiple sets of data, all array remember cleared

3: dfs in the pit of my 20 times MLE ...... remember visx, visy array will be updated

4: This practice is limited to the case of each point can be matched, if not match will use the network flow

Bipartite graph matching template title :( worth considering)

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 int V,n,m,e;
 4 vector<int> v[1005];
 5 int vis[1005],match[1005];
 6  
 7 int init()
 8 {
 9     memset(match,-1,sizeof(match));
10     scanf("%d%d%d%d",&V,&n,&m,&e);
11     for(int i=1;i<=e;i++)
12     {
13         int x,y;
14         scanf("%d%d",&x,&y); y+=n;
15         v[x].push_back(y);
16     }
17 }
18  
19 int dfs(int u)
20 {
21     for(int i=0;i<(int)v[u].size();i++)
22     {
23         int p=v[u][i];
24         if(vis[p]) continue;
25         vis[p]=1;
26         if(match[p]==-1||dfs(match[p])==1)
27         {
28             match[u]=p;
29             match[p]=u;
30             return 1;
31         }
32     }
33     return 0;
34 }
35  
36 int main()
37 {
38     int sum=0;
39     init();
40     for(int i=1;i<=n;i++)
41     {
42         if(match[i]==-1)
43         {
44             memset(vis,0,sizeof(vis));
45             if (dfs(i)) sum++;
46         }
47     }
48     printf("%d\n",min(V+1,n+m-sum));
49     return 0;
50 }

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KM template question :

 1 #include<cstdio>
 2 #include<cstring>
 3 using namespace std;
 4 const int N=305;
 5 const int inf=0X3f3f3f;
 6 
 7 int w[N][N];
 8 int n,ans=0;
 9 int lx[N],ly[N],match[N],slack[N];
10 bool visx[N],visy[N];
11 
12 
13 void init()
14 {
15     for(int i=0;i<n;i++) visy[i]=0;
16     for(int i=0;i<n;i++) visx[i]=0;
17 }
18 
19 bool dfs(int u)
20 {
21     int Delta;
22     visx[u]=1;
23     for(int v=0;v<n;++v)
24     {
25         if(visy[v]) continue;
26         Delta=lx[u]+ly[v]-w[u][v];
27         if(Delta == 0 )
 28          {
 29              visy [v] = 1 ;
30              if (match [v] == - 1 || dfs (match [v]))
 31              {
 32                  match [v] = u;
33                  return  true ;
34              }
 35          }
 36          else  if (slack [v]> Delta)
 37              slack [v] = Delta;
38      }
 39      return  false ;    
40  }
 41 
42 is  void KM ()
 43 is  {
 44 is      for ( int X = 0 ; X <n-; ++ X)
 45      {
 46 is          for ( int Y = 0 ; Y <n-; Y ++) Slack [Y] = INF; // save time outside opening 
47          the while ( to true )
 48          {
 49              the init ();
 50              IF (DFS (X)) BREAK ;
 51 is              int Delta = INF;
 52 is              for ( int J = 0 ; J <n-; J ++) IF(!visy[j]&&delta>slack[j]) delta=slack[j];
53             for(int i=0;i<n;++i) if(visx[i]) lx[i]-=delta;
54             for(int j=0;j<n;++j) 
55             {
56                 if(visy[j]) ly[j]+=delta;
57                 else slack[j]-=delta;
58             }
59         }
60     }
61 }
62 
63 int main()
64 {
65     while(scanf("%d",&n)!=EOF)
66     {
67         memset(match,-1,sizeof(match));
68         memset(ly,0,sizeof(ly));
69         for(int i=0;i<n;++i) match[i]=-1;
70         for(int i=0;i<n;++i)
71         {
72             for(int j=0;j<n;++j)
73                {
74                 scanf("%d",&w[i][j]);
75             }
76         }
77         for(int i=0;i<n;++i)
78         {
79             lx[i]=-inf;
80             for(int j=0;j<n;j++) if(lx[i]<w[i][j]) lx[i]=w[i][j];
81         }
82         KM();
83     
84         ans=0;
85         for(int i=0;i<n;++i)
86         {
87             if(match[i]!=-1) ans+=w[match[i]][i];
88         }
89         printf("%d\n",ans);
90     }
91     return 0;
92 }

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