CF1054F Electric Scheme

CF1054F Electric Scheme 

其实没啥的。

离散化后，每行每列选择一个。

但是可能会相交

每行或每列相邻两个点成为一小段。

小段按照行列左右部点

小段有交，连inf边，每个s-左，右-t，连1

最小割。

输出方案真的很麻烦。。。

 

代码难度>思维含量的网络流，，，

#include<bits/stdc++.h>
#define reg register int
#define il inline
#define fi first
#define se second
#define mk(a,b) make_pair(a,b)
#define numb (ch^'0')
#define pb push_back
#define solid const auto &
#define enter cout<<endl
#define pii pair<int,int>
using namespace std;
typedef long long ll;
template<class T>il void rd(T &x){
    char ch;x=0;bool fl=false;while(!isdigit(ch=getchar()))(ch=='-')&&(fl=true);
    for(x=numb;isdigit(ch=getchar());x=x*10+numb);(fl==true)&&(x=-x);}
template<class T>il void output(T x){if(x/10)output(x/10);putchar(x%10+'0');}
template<class T>il void ot(T x){if(x<0) putchar('-'),x=-x;output(x);putchar(' ');}
template<class T>il void prt(T a[],int st,int nd){for(reg i=st;i<=nd;++i) ot(a[i]);putchar('\n');}
namespace Modulo{
const int mod=998244353;
int ad(int x,int y){return (x+y)>=mod?x+y-mod:x+y;}
void inc(int &x,int y){x=ad(x,y);}
int mul(int x,int y){return (ll)x*y%mod;}
void inc2(int &x,int y){x=mul(x,y);}
int qm(int x,int y=mod-2){int ret=1;while(y){if(y&1) ret=mul(x,ret);x=mul(x,x);y>>=1;}return ret;}
}
//using namespace Modulo;
namespace Miracle{
const int N=1005;
const int inf=0x3f3f3f3f;
int n;
struct node{
    int nxt,to;
    int w;
}e[2*(N*N+N+N)];
int hd[2*N],cnt=1;
void add(int x,int y,int w){
    e[++cnt].nxt=hd[x];
    e[cnt].to=y;e[cnt].w=w;
    hd[x]=cnt;

    e[++cnt].nxt=hd[y];
    e[cnt].to=x;e[cnt].w=0;
    hd[y]=cnt;
}
int d[2*N];
int s,t;
int dfs(int x,int flow){
    if(x==t) return flow;
    int res=flow;
    for(reg i=hd[x];i&&res;i=e[i].nxt){
        int y=e[i].to;
        if(d[y]==d[x]+1){
            int k=dfs(y,min(res,e[i].w));
            if(!k) d[y]=0;
            res-=k;
            e[i].w-=k;
            e[i^1].w+=k;
        }
    } 
    return flow-res;
}
int q[2*N],l,r;
bool bfs(){
    l=1,r=0;
    memset(d,0,sizeof d);
    q[++r]=t;
    d[t]=t+1;
    while(l<=r){
        int x=q[l++];
        for(reg i=hd[x];i;i=e[i].nxt){
            int y=e[i].to;
            if(e[i^1].w&&!d[y]){
                d[y]=d[x]-1;
                q[++r]=y;
                if(y==s) return true;
            }
        }
    }
    return false;
}
struct po{
    int x,y;
    po(){}
    po(int xx,int yy){
        x=xx;y=yy;
    }
    void op(){
        ot(x);ot(y);
    }
}p[N];

struct line{
    int pos,l,r;
}X[N],Y[N];
int cx,cy;

int th[N],hc;
int tl[N],lc;
vector<int>hang[N],lie[N];
vector<int>ex[N],ey[N];
bool jiao(line a,line b){
    if((b.l<=a.pos&&a.pos<=b.r)&&(a.l<=b.pos&&b.pos<=a.r)) return true;
    return false;
}

bool vis[2*N];
void fin(){
    l=1,r=0;
    q[++r]=s;
    vis[s]=1;
    while(l<=r){
        int x=q[l++];
        // cout<<" fin "<<x<<endl;
        for(reg i=hd[x];i;i=e[i].nxt){
            int y=e[i].to;
            if(!vis[y]&&e[i].w){
                vis[y]=1;
                q[++r]=y;
            }
        }
    }
    // cout<<" visiv "<<endl;
    // prt(vis,s,t);
}

struct sol{
    po a,b;
}ax[N],ay[N];
int ansx,ansy;
int main(){
    rd(n);
    for(reg i=1;i<=n;++i){
        rd(p[i].x);rd(p[i].y);
        tl[++lc]=p[i].x;
        th[++hc]=p[i].y;
    }
    sort(tl+1,tl+lc+1);
    lc=unique(tl+1,tl+lc+1)-tl-1;
    sort(th+1,th+hc+1);
    hc=unique(th+1,th+hc+1)-th-1;
    for(reg i=1;i<=n;++i){
        int tx=lower_bound(tl+1,tl+lc+1,p[i].x)-tl;
        int ty=lower_bound(th+1,th+hc+1,p[i].y)-th;
        hang[ty].pb(p[i].x);
        lie[tx].pb(p[i].y);
    }
    for(reg i=1;i<=lc;++i) sort(lie[i].begin(),lie[i].end());
    for(reg i=1;i<=hc;++i) sort(hang[i].begin(),hang[i].end());
    for(reg i=1;i<=lc;++i){
        if(!lie[i].size()) continue;
        int las=lie[i][0];
        for(reg j=1;j<lie[i].size();++j){
            int now=lie[i][j];
            if(now-1>=las+1){
                ++cx;
                X[cx].pos=tl[i];
                X[cx].r=now-1;
                X[cx].l=las+1;
                ex[i].pb(cx);
            }
            las=now;
        }
    }
    for(reg i=1;i<=hc;++i){
        if(!hang[i].size()) continue;
        int las=hang[i][0];
        for(reg j=1;j<hang[i].size();++j){
            int now=hang[i][j];
            if(now-1>=las+1){
                ++cy;
                Y[cy].pos=th[i];
                Y[cy].r=now-1;
                Y[cy].l=las+1;
                ey[i].pb(cy);
            }
            las=now;
        }
    }
    s=0;t=cx+cy+1;

    for(reg i=1;i<=cx;++i){
        add(s,i,1);
        for(reg j=1;j<=cy;++j){
            if(jiao(X[i],Y[j])){
                // cout<<" jiao "<<i<<" j "<<j<<endl;
                add(i,j+cx,inf);
            }
        }
    }
    for(reg i=1;i<=cy;++i){
        add(i+cx,t,1);
    }
    
    while(bfs())while(dfs(s,inf));

    fin();
    // cout<<" cx "<<cx<<" cy "<<cy<<endl;


    for(reg i=1;i<=lc;++i){
        
        if(!lie[i].size()) continue;
        int le=lie[i][0],ri;
        for(solid now:ex[i]){
            if(vis[s]!=vis[now]){
                
                ri=X[now].l-1;
                ++ansx;
                ax[ansx].a=po(X[now].pos,le);
                ax[ansx].b=po(X[now].pos,ri);
                le=X[now].r+1;
            }
        }
        ri=lie[i][lie[i].size()-1];
        ++ansx;
        ax[ansx].a=po(tl[i],le);
        ax[ansx].b=po(tl[i],ri);
    }

    for(reg i=1;i<=hc;++i){
        // cout<<" i "<<i<<" : "<<th[i]<<endl;
        if(!hang[i].size()) continue;
        int le=hang[i][0],ri;
        for(solid now:ey[i]){
            if(vis[t]!=vis[now+cx]){
                ri=Y[now].l-1;
                ++ansy;
                // cout<<" new "<<endl;
                ay[ansy].a=po(le,Y[now].pos);
                ay[ansy].b=po(ri,Y[now].pos);
                le=Y[now].r+1;
            }
        }
        ri=hang[i][hang[i].size()-1];
        ++ansy;
        ay[ansy].a=po(le,th[i]);
        ay[ansy].b=po(ri,th[i]);
    }

    printf("%d\n",ansy);
    for(reg i=1;i<=ansy;++i){
        ay[i].a.op();ay[i].b.op();puts("");
    }
    // puts("");
    printf("%d\n",ansx);
    for(reg i=1;i<=ansx;++i){
        ax[i].a.op();ax[i].b.op();puts("");
    }
    return 0;
}

}
signed main(){
    Miracle::main();
    return 0;
}

/*
   Author: *Miracle*
*/