CodeForces 269C Flawed Flow 拓扑

//平衡出入流
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<string.h>
#include<algorithm>
#include<stack>
using namespace std;
const int maxn=300000;
const int maxm=600000;
int n;

struct node
{
int u,v,w,next,id;
}edge[maxm];

int in[maxn],out[maxn];
int em;
int head[maxn];

void addedge(int u,int v,int w,int _id)
{
edge[em].id=_id;
edge[em].u=u;
edge[em].v=v;
edge[em].w=w;
edge[em].next=head[u];
head[u]=em++;
}

stack<int>q;
int dir[maxm];
int e1[maxn],e2[maxn];

void topo()
{
while(!q.empty()) q.pop();
q.push(1);
in[1]=out[1]=0;
while(!q.empty())
{
int u=q.top();
q.pop();
for(int i=head[u];~i;i=edge[i].next)
{
int v=edge[i].v;
if(in[v]==out[v] && v!=n) continue;
in[v]+=edge[i].w;
//           cout<<v<<" "<<in[v]<<" "<<out[v]<<endl;
if(in[v]==out[v] && v!=n) q.push(v);
int _id=edge[i].id;
//           cout<<v<<" "<<_id<<endl;
if(v==e1[_id])
dir[_id]=1;
}
}
}

int tu,tv,tw;

int main()
{
//    freopen("in.txt","r",stdin);
int m;
while(scanf("%d%d",&n,&m)!=EOF)
{
em=0;
memset(head,-1,sizeof(head));
memset(in,0,sizeof(in));
memset(out,0,sizeof(out));
memset(dir,0,sizeof(dir));
for(int i=1;i<=m;i++)
{
scanf("%d%d%d",&tu,&tv,&tw);
e1[i]=tu;
e2[i]=tv;
addedge(tu,tv,tw,i);
addedge(tv,tu,tw,i);
out[tu]+=tw;
out[tv]+=tw;
}
for(int i=1;i<=n;i++)
out[i]=out[i]>>1;
out[1]=0;
topo();
for(int i=1;i<=m;i++)
{
printf("%d\n",dir[i]);
}
}
return 0;

}