KM algorithm template hdu 2255

KM matching algorithm in the case is complete to find the best match.

First of all, the first range as the largest, if not the biggest case to meet, on the decline continues a dimension match.

Until a successful match.

 1 #include<cstdio>
 2 #include<string.h>
 3 #include<algorithm>
 4 using namespace std;
 5 const int maxn=3e2+10;
 6 const int inf=0x3f3f3f3f;
 7 int G[maxn][maxn],n;
 8 int lx[maxn],ly[maxn];
 9 int match[maxn];
10 int visx[maxn],visy[maxn];
11 void init()
12 {
13     memset(match,0,sizeof(match));
14 }
15 int dfs(int k)
16 {
17     visx[k]=1;
18     for(int i=1;i<=n;i++){
19         if(!visy[i]&&G[k][i]==lx[k]+ly[i]){
20             visy[i]=1;
21             if(!match[i]||dfs(match[i])){
22                 match[i]=k;
23                 return 1;
24             }
25         }
26     }
27     return 0;
28 }
29 int KM()
30 {
31     for(int i=1;i<=n;i++){
32         lx[i]=-inf,ly[i]=0;
33         for(int j=1;j<=n;j++)
34             lx[i]=max(lx[i],G[i][j]);
35     }
36     for(int k=1;k<=n;k++){
37         while(1){
38             memset(visx,0,sizeof(visx));
39             memset(visy,0,sizeof(visy));
40             if(dfs(k)) break;
41             int mn=inf;
42 
43             for(int i=1;i<=n;i++) if(visx[i])
44             for(int j=1;j<=n;j++) if(!visy[j])
45             mn=min(mn,lx[i]+ly[j]-G[i][j]);
46             if(mn==inf) return -1;
47             for(int i=1;i<=n;i++) if(visx[i]) lx[i]-=mn;
48             for(int i=1;i<=n;i++) if(visy[i]) ly[i]+=mn;
49         }
50     }
51     int ans=0;
52     for(int i=1;i<=n;i++) if(match[i])
53     ans+=G[match[i]][i];
54     return ans;
55 }
56 int main()
57 {
58     while(scanf("%d",&n)!=EOF){
59         init();
60         for(int i=1;i<=n;i++)
61         for(int j=1;j<=n;j++)
62         scanf("%d",&G[i][j]);
63         printf("%d\n",KM());
64     }
65     return 0;
66 }