带花树（一般图最大匹配）

#define N 45#define SET(a,b) memset(a,b,sizeof(a))deque<int> Q;//g[i][j]存放关系图：i,j是否有边,match[i]存放i所匹配的点//建图开始初始化g//最终匹配方案为match//复杂度O(n^3)//点是从1到n的 bool g[N][N],inque[N],inblossom[N];int match[N],pre[N],base[N];//找公共祖先int findancestor(int u,int v){    bool inpath[N]={false};    while(1)    {        u=base[u];        inpath[u]=true;        if(match[u]==-1)break;        u=pre[match[u]];    }    while(1)    {        v=base[v];        if(inpath[v])return v;        v=pre[match[v]];    }}//压缩花void reset(int u,int anc){    while(u!=anc)    {        int v=match[u];        inblossom[base[u]]=1;        inblossom[base[v]]=1;        v=pre[v];        if(base[v]!=anc)pre[v]=match[u];        u=v;    }}void contract(int u,int v,int n){    int anc=findancestor(u,v);    SET(inblossom,0);    reset(u,anc);reset(v,anc);    if(base[u]!=anc)pre[u]=v;    if(base[v]!=anc)pre[v]=u;    for(int i=1;i<=n;i++)        if(inblossom[base[i]])        {            base[i]=anc;            if(!inque[i])            {                Q.push_back(i);                inque[i]=1;            }        }}bool dfs(int S,int n){    for(int i=0;i<=n;i++)pre[i]=-1,inque[i]=0,base[i]=i;    Q.clear();Q.push_back(S);inque[S]=1;    while(!Q.empty())    {        int u=Q.front();Q.pop_front();        for(int v=1;v<=n;v++)        {            if(g[u][v]&&base[v]!=base[u]&&match[u]!=v)            {                if(v==S||(match[v]!=-1&&pre[match[v]]!=-1))contract(u,v,n);                else if(pre[v]==-1)                {                    pre[v]=u;                    if(match[v]!=-1)Q.push_back(match[v]),inque[match[v]]=1;                    else                    {                        u=v;                        while(u!=-1)                        {                            v=pre[u];                            int w=match[v];                            match[u]=v;                            match[v]=u;                            u=w;                        }                        return true;                    }                }            }        }    }    return false;}int solve(int n){    SET(match,-1);    int ans=0;    for(int i=1;i<=n;i++)        if(match[i]==-1&&dfs(i,n))            ans++;    return ans;}