poj1325

最小点集覆盖

匈牙利算法

View Code
   
     
#include < iostream >
#include
< cstdio >
#include
< cstdlib >
#include
< cstring >
using namespace std;

#define maxn 105

int n, uN, vN;
bool g[maxn][maxn];
int xM[maxn], yM[maxn];
bool chk[maxn];

bool SearchPath( int u)
{
int v;
for (v = 0 ; v < vN; v ++ )
if (g[u][v] && ! chk[v])
{
chk[v]
= true ;
if (yM[v] == - 1 || SearchPath(yM[v]))
{
yM[v]
= u;
xM[u]
= v;
return true ;
}
}
return false ;
}

int MaxMatch()
{
int u, ret = 0 ;
memset(xM,
- 1 , sizeof (xM));
memset(yM,
- 1 , sizeof (yM));
for (u = 0 ; u < uN; u ++ )
if (xM[u] == - 1 )
{
memset(chk,
false , sizeof (chk));
if (SearchPath(u))
ret
++ ;
}
return ret;
}

void input()
{
scanf(
" %d%d " , & vN, & n);
memset(g,
0 , sizeof (g));
for ( int i = 0 ; i < n; i ++ )
{
int a, b, c;
scanf(
" %d%d%d " , & a, & b, & c);
if (b && c)
g[b][c]
= true ;
}
}

int main()
{
// freopen("t.txt", "r", stdin);
while (scanf( " %d " , & uN), uN)
{
input();
int ans = MaxMatch();
printf(
" %d\n " , ans);
}
return 0 ;
}

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