[bzoj]1305: [Cqoi2009]dance dancing two points + network stream

Description

There were n boys and n Girls at a dance. At the beginning of each song, all the boys and girls fit into the N-dance ballroom. Every boy will not dance with the same girl for two (or more) dance songs. There are some boys and girls who like each other, while others dislike each other (not "one-way Likes"). Each boy is willing to dance with the K-not-like girls at most, and each girl is willing to dance with the K-not-liked boys at most. Given the information about whether each pair of boys and girls like each other, the ball can have a few dance songs. The following:

Simple two-point + network flow, a problem of water, two points can have a few dance, and then use the network flow to judge, directly in accordance with the test instructions edge, and the most and k do not like the dance of this condition, I was so dealt with, each boy girl split into two points, an expression and it likes to dance, an expression and it does not like the dance. Code:

#include <bits/stdc++.h> using namespace std;
#define LL Long Long const int inf=2147483647;
const int maxn=60;
    int read () {int X=0,f=1;char ch=getchar (); while (ch< ' 0 ' | |
    Ch> ' 9 ') {if (ch== '-') F=-1;ch=getchar ();}
    while (ch>= ' 0 ' &&ch<= ' 9 ') {x= (x<<3) + (x<<1) +ch-' 0 '; Ch=getchar ();}
return x*f; } struct Edge{int y,d,next;}
E[500000];
int Last[maxn*4],len;
    void ins (int x,int y,int d) {int t=++len;
    E[t].y=y;e[t].d=d;
e[t].next=last[x];last[x]=t;
} void Addedge (int x,int y,int D) {ins (x,y,d); ins (y,x,0);} int n,k;
BOOL In[maxn*4];
queue<int>q;
int h[maxn*4],st,ed;
    BOOL BFs () {memset (h,0,sizeof (h)); h[st]=1;
    Q.push (ST);
        while (!q.empty ()) {int X=q.front (); Q.pop ();
    for (int i=last[x];i;i=e[i].next) if (E[i].d&&!h[e[i].y]) H[e[i].y]=h[x]+1,q.push (E[I].Y);
} return h[ed];
    } int dfs (int x,int f) {if (x==ed) return F;
    int s=0,t; for (int i=last[x];i;i=e[i].next) {iNT Y=E[I].Y;
            if (h[y]==h[x]+1&&e[i].d&&s<f) {T=dfs (Y,min (F-S,E[I].D));
        s+=t;e[i^1].d+=t;e[i].d-=t;
    }} if (s==0) h[x]=0;
return s;
} bool LIKE[MAXN][MAXN];
    Boys 1~n Boys 2 n+1~2n schoolgirl 2n+1~3n schoolgirl 2 3n+1~4n bool Check (int x) {if (x==0) return true;
    Memset (Last,0,sizeof (last)); len=1;
    st=4*n+1;ed=4*n+2;
        for (int i=1;i<=n;i++) {Addedge (st,i,x);
        Addedge (I,I+N,K);
        for (int j=1;j<=n;j++) if (Like[i][j]) Addedge (i,j+2*n,1);
    else Addedge (i+n,j+3*n,1);
        } for (int i=1;i<=n;i++) {Addedge (i+2*n,ed,x);
    Addedge (I+3*N,I+2*N,K);
    } int ans=0;
    while (BFS ())) Ans+=dfs (St,inf);
return ans==n*x;
    } int main () {n=read (); K=read ();
        for (int i=1;i<=n;i++) {char STR[MAXN];
        scanf ("%s", str+1);
    for (int j=1;j<=n;j++) if (str[j]== ' Y ') like[i][j]=true;
    } int l=0,r=n;
  while (L&LT;=R)  {int mid=l+r>>1;
        if (check (mid)) l=mid+1;
    else r=mid-1;
} printf ("%d", l-1); }