hdu 2255 奔小康赚大钱 最大权匹配KM

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<cstdlib>
 5 #include<cmath>
 6 #include<algorithm>
 7 #include<vector>
 8 #include<queue>
 9 #define inf 0x7fffffff
10 using namespace std;
11 const int maxn=300+10;
12 
13 int n,nx,ny;
14 int lx[maxn],ly[maxn],visx[maxn],visy[maxn];
15 int link[maxn],slack[maxn];
16 int w[maxn][maxn];
17 
18 int dfs(int x)
19 {
20     visx[x]=1;
21     for (int y=1 ;y<=ny ;y++)
22     {
23         if (visy[y]) continue;
24         int t=lx[x]+ly[y]-w[x][y];
25         if (t==0)
26         {
27             visy[y]=1;
28             if (link[y]==-1 || dfs(link[y]))
29             {
30                 link[y]=x;
31                 return 1;
32             }
33         }
34         else if (slack[y]>t) slack[y]=t;
35     }
36     return 0;
37 }
38 
39 int KM()
40 {
41     memset(ly,0,sizeof(ly));
42     memset(link,-1,sizeof(link));
43     for (int x=1 ;x<=nx ;x++)
44     {
45         lx[x]=-inf;
46         for (int y=1 ;y<=ny ;y++)
47             lx[x]=max(lx[x],w[x][y]);
48     }
49     for (int x=1 ;x<=nx ;x++)
50     {
51         for (int j=1 ;j<=ny ;j++) slack[j]=inf;
52         while (1)
53         {
54             memset(visx,0,sizeof(visx));
55             memset(visy,0,sizeof(visy));
56             if (dfs(x)) break;
57             int d=inf;
58             for (int j=1 ;j<=ny ;j++)
59             {
60                 if (!visy[j] && slack[j]<d)
61                     d=slack[j];
62             }
63             for (int i=1 ;i<=nx ;i++)
64                 if (visx[i]) lx[i] -= d;
65             for (int i=1 ;i<=ny ;i++)
66             {
67                 if (visy[i]) ly[i] += d;
68                 else slack[i] -= d;
69             }
70         }
71     }
72     int ans=0;
73     for (int i=1 ;i<=ny ;i++)
74         if (link[i]!=-1) ans += w[link[i] ][i];
75     return ans;
76 }
77 
78 int main()
79 {
80     while (scanf("%d",&n)!=EOF)
81     {
82         nx=ny=n;
83         for (int i=1 ;i<=n ;i++)
84         {
85             for (int j=1 ;j<=n ;j++)
86                 scanf("%d",&w[i][j]);
87         }
88         printf("%d\n",KM());
89     }
90     return 0;
91 }