bzoj1305: [CQOI2009]dance跳舞

#include<cstdio>
#include<iostream>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<cmath>
using namespace std;

struct node
{
    int x,y,c,next,other;
}a[2100000];int len,last[110000];
void ins(int x,int y,int c)
{
    if(c==0)return ;
    int k1,k2;
    
    len++;k1=len;
    a[len].x=x;a[len].y=y;a[len].c=c;
    a[len].next=last[x];last[x]=len;
    //printf("%d %d %d\n",x,y,c);
    
    len++;k2=len;
    a[len].x=y;a[len].y=x;a[len].c=0;
    a[len].next=last[y];last[y]=len;
    
    a[k1].other=k2;
    a[k2].other=k1;
}
int st,ed;
int h[110000],list[110000];
bool bt_h()
{
    memset(h,0,sizeof(h));h[st]=1;
    int head=1,tail=2;list[1]=st;
    while(head!=tail)
    {
        int x=list[head];
        for(int k=last[x];k;k=a[k].next)
        {
            int y=a[k].y;
            if(h[y]==0&&a[k].c>0)
            {
                h[y]=h[x]+1;
                list[tail]=y;
                tail++;
            }
        }
        head++;
    }
    if(h[ed]==0)return false;
    return true;
}
int findflow(int x,int f)
{
    if(x==ed)return f;
    int s=0;
    for(int k=last[x];k;k=a[k].next)
    {
        int y=a[k].y;
        if(h[y]==h[x]+1&&a[k].c>0&&s<f)
        {
            int t=findflow(y,min(a[k].c,f-s));
            s+=t;a[k].c-=t;a[a[k].other].c+=t;
        }
    }
    if(s==0)h[x]=0;
    return s;
}

//-------findflow----------

int n,k;
int Yb[110],Yg[110];char mp[110][110];
bool check(int mid)
{
    //st->boy(1~n)->bl(n+1~n*2)、bu(n*2+1~n*3)->
    //gl(n*3+1~n*4)、gu(n*4+1~n*5)->girl(n*5+1,n*6)->ed
    
    st=n*6+1,ed=n*6+2;
    len=0;memset(last,0,sizeof(last));
    
    for(int i=1;i<=n;i++)
        ins(st,i,mid), ins(i+n*5,ed,mid);
        
    for(int i=1;i<=n;i++)
    {
        int B=i,bl=i+n,bu=i+2*n;
        ins(B,bl,Yb[i]);
        ins(B,bu,k);
        
        int G=i+n*5,gl=i+n*3,gu=i+n*4;
        ins(gl,G,Yg[i]);
        ins(gu,G,k);
    }
    
    for(int B=1;B<=n;B++)
    {
        int bl=B+n,bu=B+2*n;
        for(int G=1;G<=n;G++)
        {
            int gl=G+n*3,gu=G+n*4;
            if(mp[B][G]==‘Y‘)ins(bl,gl,1);
            else ins(bu,gu,1);
        }
    }
    
    //-----composition-------
    
    int ans=0;
    while(bt_h()==true)
    {
        ans+=findflow(st,999999999);
    }
    if(ans==n*mid)return true;
    return false;
}

int main()
{
    //freopen("dance.in","r",stdin);
    //freopen("dance.out","w",stdout);
    
    scanf("%d%d",&n,&k);
    for(int i=1;i<=n;i++)scanf("%s",mp[i]+1);
    
    memset(Yb,0,sizeof(Yb));
    memset(Yg,0,sizeof(Yg));
    for(int i=1;i<=n;i++)
        for(int j=1;j<=n;j++)
            if(mp[i][j]==‘Y‘) Yb[i]++, Yg[j]++;
    
    
    int l=1,r=n,ans=0;
    while(l<=r)
    {
        int mid=(l+r)/2;
        if(check(mid)==true)
        {
            l=mid+1;
            ans=mid;
        }
        else r=mid-1;
    }
    printf("%d\n",ans);
    
    return 0;
}