HDOJ 5348 MZL's endless loop 乱搞

对每个点DFS,根据入度和出度的情况选择标记入边或者出边进行DFS

MZL's endless loop

Time Limit: 3000/1500 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)
Total Submission(s): 1037    Accepted Submission(s): 206
Special Judge

Problem Description

As we all kown, MZL hates the endless loop deeply, and he commands you to solve this problem to end the loop.
You are given an undirected graph with  n  vertexs and  m  edges. Please direct all the edges so that for every vertex in the graph the inequation  |out degree − in degree|≤1  is satisified.
The graph you are given maybe contains self loops or multiple edges.

 

Input

The first line of the input is a single integer  T , indicating the number of testcases.
For each test case, the first line contains two integers  n  and  m .
And the next  m  lines, each line contains two integers  ui  and  vi , which describe an edge of the graph.
T≤100 ,  1≤n≤105 ,  1≤m≤3∗105 ,  ∑n≤2∗105 ,  ∑m≤7∗105 .

 

Output

For each test case, if there is no solution, print a single line with  −1 , otherwise output  m  lines,.
In  i th line contains a integer  1  or  0 ,  1  for direct the  i th edge to  ui→vi ,  0  for  ui←vi .

 

Sample Input

   
   
   
   

    
    
    
    2
3 3
1 2
2 3
3 1
7 6
1 2
1 3
1 4
1 5
1 6
1 7
   
   
   
   

 

Sample Output

   
   
   
   

    
    
    
    1
1
1
0
1
0
1
0
1
   
   
   
   

 

Source

2015 Multi-University Training Contest 5

 

/* ***********************************************
Author        :CKboss
Created Time  :2015年08月05日 星期三 10时51分53秒
File Name     :HDOJ5348.cpp
************************************************ */

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>
#include <cmath>
#include <cstdlib>
#include <vector>
#include <queue>
#include <set>
#include <map>

#pragma comment(linker, "/STACK:102400000,102400000")

using namespace std;

const int maxn=100100;

int n,m;

struct Edge
{
    int to,next;
}edge[maxn*6];

int Adj[maxn],Size;

void init()
{
    memset(Adj,-1,sizeof(Adj)); Size=0;
}


void Add_Edge(int u,int v)
{
    edge[Size].to=v;
    edge[Size].next=Adj[u];
    Adj[u]=Size++;
}

bool vis[maxn*6];
int ans[maxn*3],in[maxn],out[maxn],num[maxn];

void clear()
{
    init();
    memset(ans,0,sizeof(ans));
    memset(vis,0,sizeof(vis));
    memset(num,0,sizeof(num));
    memset(in,0,sizeof(in));
    memset(out,0,sizeof(out));
}

/// u--->v
void dfs0(int u)
{
    for(int i=Adj[u];~i;i=edge[i].next)
    {
        if(vis[i]==true)
        {
            Adj[u]=edge[i].next; continue;
        }

        int v=edge[i].to;

        if(v!=u&&in[v]>out[v]) continue;

        vis[i]=vis[i^1]=true;

        if(i%2==0) ans[i/2]=0;
        else ans[i/2]=1;

        out[u]++; in[v]++;

        Adj[u]=edge[i].next;
        dfs0(v);

        return ;
    }
}

/// u<----v
void dfs1(int u)
{
    for(int i=Adj[u];~i;i=edge[i].next)
    {
        if(vis[i]==true)
        {
            Adj[u]=edge[i].next;
            continue;
        }

        int v=edge[i].to;

        if(v!=u&&in[v]<out[v]) continue;

        vis[i]=vis[i^1]=true;

        if(i%2==0) ans[i/2]=1;
        else ans[i/2]=0;

        out[v]++; in[u]++;

        Adj[u]=edge[i].next;
        dfs1(v);

        return ;
    }
}

int main()
{
    //freopen("in.txt","r",stdin);
    //freopen("out.txt","w",stdout);

    int T_T;
    scanf("%d",&T_T);
    while(T_T--)
    {
        clear();
        scanf("%d%d",&n,&m);

        for(int i=0,u,v;i<m;i++)
        {
            scanf("%d%d",&u,&v);
            /// edgeid Size/2;
            Add_Edge(u,v); /// Size%2==0 real edge
            Add_Edge(v,u);
            num[u]++; num[v]++;
        }
        
        for(int i=1;i<=n;i++)
        {
            while(in[i]+out[i]!=num[i])
            {
                if(in[i]>=out[i]) dfs0(i);
                else dfs1(i);
            }
        }

        for(int i=0;i<m;i++)
            printf("%d\n",ans[i]);
    }
    
    return 0;
}