HDU2255-奔小康赚大钱-二分图最大权值匹配-KM算法

Posted 2020-08-05 Helica

二分图最大权值匹配问题。用KM算法。

最小权值的时候把权值设置成相反数

  1 /*--------------------------------------------------------------------------------------*/
  2 
  3 #include <algorithm>
  4 #include <iostream>
  5 #include <cstring>
  6 #include <ctype.h>
  7 #include <cstdlib>
  8 #include <cstdio>
  9 #include <vector>
 10 #include <string>
 11 #include <queue>
 12 #include <stack>
 13 #include <cmath>
 14 #include <set>
 15 #include <map>
 16 
 17 //debug function for a N*M array
 18 #define debug_map(N,M,G) printf("\n");for(int i=0;i<(N);i++) 19 {for(int j=0;j<(M);j++){ 20 printf("%d",G[i][j]);}printf("\n");}
 21 //debug function for int,float,double,etc.
 22 #define debug_var(X) cout<<#X"="<<X<<endl;
 23 #define LL long long
 24 const int INF = 0x3f3f3f3f;
 25 const LL LLINF = 0x3f3f3f3f3f3f3f3f;
 26 /*--------------------------------------------------------------------------------------*/
 27 using namespace std;
 28 
 29 int N,M,T;
 30 const int maxn = 310;
 31 int nx,ny;
 32 int g[maxn][maxn];
 33 int linker[maxn],lx[maxn],ly[maxn];
 34 int slack[maxn];
 35 bool visx[maxn],visy[maxn];
 36 bool DFS(int x)
 37 {
 38     visx[x] = true;
 39     for(int y=0;y<ny;y++)
 40     {
 41         if(visy[y]) continue;
 42         int tmp = lx[x] + ly[y] - g[x][y];
 43         if(tmp == 0)
 44         {
 45             visy[y] = true;
 46             if(linker[y] == -1 || DFS(linker[y]))
 47             {
 48                 linker[y] = x;
 49                 return true;
 50             }
 51         }
 52         else if(slack[y] > tmp) slack[y] = tmp;
 53     }
 54     return false;
 55 }
 56 int KM()
 57 {
 58     memset(linker,-1,sizeof linker);
 59     memset(ly,0,sizeof ly);
 60     for(int i=0;i<nx;i++)
 61     {
 62         lx[i] = -INF;
 63         for(int j=0;j<ny;j++)   lx[i] = max(lx[i],g[i][j]);
 64     }
 65     for(int x=0;x<nx;x++)
 66     {
 67         for(int i=0;i<ny;i++) slack[i] = INF;
 68         while(true)
 69         {
 70             memset(visx,false,sizeof visx);
 71             memset(visy,false,sizeof visy);
 72             if(DFS(x)) break;
 73             int d = INF;
 74             for(int i=0;i<ny;i++) if(!visy[i] && d > slack[i]) d = slack[i];
 75             for(int i=0;i<nx;i++) if(visx[i]) lx[i] -= d;
 76             for(int i=0;i<ny;i++)
 77             {
 78                 if(visy[i]) ly[i] += d;
 79                 else slack[i] -= d;
 80             }
 81         }
 82     }
 83     int res = 0;
 84     for(int i=0;i<ny;i++) if(linker[i] != -1) res += g[linker[i]][i];
 85     return res;
 86 }
 87 int main()
 88 {
 89     while(~scanf("%d",&N))
 90     {
 91         for(int i=0;i<N;i++)
 92         {
 93             for(int j=0;j<N;j++)
 94             {
 95                 scanf("%d",&g[i][j]);
 96             }
 97         }
 98         nx = ny = N;
 99         printf("%d\n",KM());
100     }
101 }