P4126 [AHOI2009]最小割

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<queue>
using namespace std;
typedef long long ll;
inline 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<<1)+(x<<3)+(ch^48); ch=getchar(); }
    return x*f;
}
const int N=1e5+7,M=4e6+7,INF=1e9+7;
int fir[N],from[M],to[M],val[M],cntt=1;
inline void add(int a,int b,int c)
{
    from[++cntt]=fir[a]; fir[a]=cntt;
    to[cntt]=b; val[cntt]=c;
    from[++cntt]=fir[b]; fir[b]=cntt;
    to[cntt]=a; val[cntt]=0;
}
int n,m;
int dep[N],Fir[N],S,T;
queue <int> q;
bool BFS()
{
    for(int i=1;i<=n;i++) Fir[i]=fir[i],dep[i]=0;
    q.push(S); dep[S]=1; int x;
    while(!q.empty())
    {
        x=q.front(); q.pop();
        for(int i=fir[x];i;i=from[i])
        {
            int &v=to[i]; if(dep[v]||!val[i]) continue;
            dep[v]=dep[x]+1; q.push(v);
        }
    }
    return dep[T]>0;
}
int DFS(int x,int mxf)
{
    if(x==T||!mxf) return mxf;
    int fl=0,res;
    for(int &i=Fir[x];i;i=from[i])
    {
        int &v=to[i]; if(dep[v]!=dep[x]+1||!val[i]) continue;
        if( res=DFS(v,min(mxf,val[i])) )
        {
            mxf-=res; fl+=res;
            val[i]-=res; val[i^1]+=res;
            if(!mxf) break;
        }
    }
    return fl;
}
inline int Dinic() { int res=0; while(BFS()) res+=DFS(S,INF); return res; }

int dfs_clock,dfn[N],low[N],bel[N],cnt,st[N],Top;
void Tarjan(int x)
{
    dfn[x]=low[x]=++dfs_clock; st[++Top]=x;
    for(int i=fir[x];i;i=from[i])
    {
        int &v=to[i]; if(!val[i]) continue;
        if(!dfn[v]) Tarjan(v),low[x]=min(low[x],low[v]);
        else if(!bel[v]) low[x]=min(low[x],dfn[v]);
    }
    if(dfn[x]==low[x])
    {
        cnt++;
        while(st[Top]!=x) bel[st[Top--]]=cnt;
        bel[st[Top--]]=cnt;
    }
}
int main()
{
    n=read(),m=read(),S=read(),T=read();
    int a,b,c;
    for(int i=1;i<=m;i++)
    {
        a=read(),b=read(),c=read();
        add(a,b,c);
    }
    Dinic();
    for(int i=1;i<=n;i++) if(!bel[i]) Tarjan(i);
    for(int i=2;i<cntt;i+=2)
    {
        int v=to[i],u=to[i^1];
        if(!val[i]&&bel[u]!=bel[v]) printf("1 ");
        else printf("0 ");
        if(!val[i]&&bel[S]==bel[u]&&bel[T]==bel[v]) printf("1\n");
        else printf("0\n");
    }
    return 0;
}