[CQOI2009][BZOJ1305] dance跳舞

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<vector>
#include<queue>
#include<map>
#include<set>
#define MAXN 300
#define MAXE 100000
#define INF 100000007
using namespace std;
char c[100];
int n,k,mx,T,tot,cnt,head[MAXN],dis[MAXN],q[MAXN];
int next[MAXE],key0[MAXE],key[MAXE],list[MAXE];
void insert(int x,int y,int z)
{
    next[++tot]=head[x];
    head[x]=tot;
    list[tot]=y;
    key0[tot]=z;
}
void rebuild(int x)
{
    for (int i=2;i<=cnt;i++)
        key[i]=key0[i];
    for (int i=cnt+1;i<=tot;i+=2)
        key[i]=x;
    for (int i=cnt+2;i<=tot;i+=2)
        key[i]=0;
}
bool BFS()
{
    memset(dis,0xff,sizeof(dis));
    int t=0,w=1,x;
    dis[0]=1;q[1]=0;
    while (t<w)
    {
        x=q[++t];
        for (int i=head[x];i;i=next[i])
            if (key[i]&&dis[list[i]]==-1)
            {
                dis[list[i]]=dis[x]+1;
                q[++w]=list[i];
            }
    }
    return dis[T]!=-1;
}
int find(int x,int flow)
{
    if (x==T) return flow;
    int used=0,w;
    for (int i=head[x];i;i=next[i])
        if (key[i]&&dis[list[i]]==dis[x]+1)
        {
                                            w=find(list[i],min(key[i],flow-used));
                                            key[i]-=w;
                                            key[i^1]+=w;
                                            used+=w;
                                            if (used==flow) return flow;
        }
    if (!used) dis[x]=-1;
    return used;
}
bool dinic(int x)
{
    int ans=0;
    while (BFS()) ans+=find(0,INF);
    if (ans>=x*n) return 1; return 0;
}
int main()
{
    scanf("%d%d",&n,&k);
    T=4*n+1;
    tot=1;
    for (int i=1;i<=n;i++) 
    {
        scanf("%s",c);
        for (int j=0;j<n;j++)
            if (c[j]==‘Y‘) 
            {
                insert(i,j+1+3*n,1);
                insert(j+1+3*n,i,0);
            }
            else 
            {
                insert(i+n,j+1+2*n,1);
                insert(j+1+2*n,i+n,0);
            }
    }
    for (int i=1;i<=n;i++)
    {
        insert(i,i+n,k);
        insert(i+n,i,0);
        insert(i+2*n,i+3*n,k);
        insert(i+3*n,i+2*n,0);
    }
    cnt=tot;
    for (int i=1;i<=n;i++)
    {
        insert(0,i,0);
        insert(i,0,0);
        insert(i+3*n,T,0);
        insert(T,i+3*n,0);
    }
    int l=0,r=n;
    while (l<=r)
    {
        int mid=(l+r)>>1;
        rebuild(mid);
        if (dinic(mid)) 
        {
            mx=mid;
            l=mid+1;
        }
        else r=mid-1;
    }
    printf("%d",mx);
    return 0;
}