POJ 3692 Kindergarten ( 最大独立点集 )

这道题是求最大独立点集！

最大独立点集=N - 最小顶点覆盖=N-最大匹配。

反建图，将不认识的连上边！

代码：

#include <cstdio>
#include <cstring>

const int N = 220;
int ln, rn, M;
int bmap

, cy
;
bool used
;

bool dfs( int u )
{
for ( int v = 1; v <= rn; ++v ) if ( bmap[u][v] && !used[v] ) {
used[v] = 1;
if ( cy[v] == -1 || dfs( cy[v] ) ) {
cy[v] = u;
return 1;
}
}
return false;
}
int match()
{
int res = 0;
memset(cy, -1, sizeof(cy));
for ( int i = 1; i <= ln; ++i ) {
memset( used, 0, sizeof(used));
if ( dfs(i) ) res++;
}
return res;
}
int main()
{
int icase = 1;
while ( scanf("%d%d%d", &ln, &rn, &M) == 3 && M+ln+rn ) {
for ( int i = 0; i <= ln; ++i )
for ( int j = 0; j <= rn; ++j ) bmap[i][j] = 1;
while ( M-- ) {
int u, v;
scanf("%d%d", &u, &v);
bmap[u][v] = 0;
}
printf("Case %d: %d\n", icase++, ln+rn-match());
}
}