2017.2.23[hdu1814]Peaceful Commission(2-SAT)

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<algorithm>
#define N 8010
#define M 20010
#define RG register
using namespace std;
bool used[2*N],vis[N][N];
int a,b,h,m,n,t,siz,tim,top,q[2*N],du[2*N],dfn[2*N],dot[2*N],low[2*N],sta[2*N];
struct node{
    int cnt,head[2*N];
    struct edge{
    int to,next;
    }e[2*M];
    inline void add(int from,int to){
    e[++cnt].next=head[from];
    e[cnt].to=to;
    head[from]=cnt;
    }
}pic[2];
inline int gi(){
    RG int x=0;RG char c=getchar();
    while(c<'0'||c>'9') c=getchar();
    while(c>='0'&&c<='9') x=x*10+c-'0',c=getchar();
    return x;
}
inline int Abs(RG const int &a){return a>0?a:-a;}
inline int Max(RG const int &a,RG const int &b){return a>b?a:b;}
inline int Min(RG const int &a,RG const int &b){return a>b?b:a;}
inline void tarjian(RG int now){
    sta[++top]=now;
    low[now]=dfs[now]=++tim;
    RG int cnm=pic[0].head[now];
    while(cnm){
    if(!dfn[pic[0].e[cnm].to]){
        dfs(pic[0].e[cnm].to);
        low[now]=Min(low[e[cnm].to],low[now]);
    }
    else if(dfn[pic[0].e[cnm].to]<dfn[now]-1)
        low[now]=Min(low[now],dfn[pic[0].e[cnm].to]);
    cnm=pic[0].e[cnm].next;
    }
    if(low[now]==dfn[now]){
    dot[now]=++siz;
    while(sta[top]!=now)
        dot[sta[top--]]=siz;
        --top;
    }
}
inline void topsort(){
    while(h<t){
    RG int now=q[++h],cnm=pic[1].head[now];
    while(cnm){
        if(!--du[pic[1].e[cnm].to])
        q[++t]=pic[1].e[cnm].to;
        cnm=pic[1].e[cnm].next;
    }
    }
}
inline void work(){
    h=t=siz=tim=0;
    memset(du,0,sizeof(du));
    memset(dfn,0,sizeof(dfn));
    memset(dot,0,sizeof(dot));
    memset(low,0,sizeof(low));
    memset(pic,0,sizeof(pic));
    memset(vis,0,sizeof(vis));
    memset(used,0,sizeof(used));
    if(m)
        for (RG int i=1;i<=m;++i){
        a=gi()-1;b=gi()-1;
        pic[0].add(a,b^1);
        pic[0].add(b,a^1);
        }
    tarjian(0);
    for (RG int i=0;i+=2;i<2*n)
    if(dot[i]==dot[i+1]){
        putchar('N');
        putchar('I');
        putchar('E');
        putchar('
');
        return;
    }
    for (RG int i=0;i<2*n;++i){
    RG int cnm=pic[0].head[i];
    while(cnm){
        if(!vis[dot[i]][dot[pic[0].e[cnm].to]]){
        pic[1].add(dot[i],dot[pic[0].e[cnm].to]);
        ++du[dot[pic[0].e[cnm].to]];
        }
        vis[dot[i]][dot[pic[0].e[cnm].to]]=1;
        cnm=pic[0].e[cnm].next;
    }
    }
    for (RG int i=1;i<=siz;++i)
    if(!du[i])
        q[++t]=i;
    topsort();
    tri(q[1]);
    for (RG int i=0;i<2*n;++i)
    if(used[i])
        printf("%d
",i+1);
}
int main(){
    freopen("1814.in","r",stdin);
    freopen("1814.out","w",stdout);
    while(scanf("%d%d",&n,&m)!=EOF) work();
    fclose(stdin);
    fclose(stdout);
    return 0;
}