题目大意: 相邻两点需染成两种不同颜色,问是否可以做到
解题思想: dfs
代码:
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#define maxn 1005
using namespace std;
int map[maxn][maxn];
int vis[maxn];
bool color[maxn];
int n, m, flag;
int dfs(int u)
{
for(int i=0;i<n;i++)
{
if(map[u][i]!=0)
{
if(vis[i]==0)
{
vis[i]=1;
color[i]=!color[u];
dfs(i);
}
else if(color[u]==color[i])return 0;
}
}
return 1;
}
int main()
{
while(~scanf("%d",&n)&&n!=0)
{
memset(map,0,sizeof(map));
memset(vis,0,sizeof(vis));
cin>>m;
while(m--)
{
int u,v;cin>>u>>v;
map[u][v]=map[v][u]=1;
}
color[0]=true;vis[0]=1;
if(dfs(0)==1) cout<<"BICOLORABLE."<<endl;
else cout<<"NOT BICOLORABLE."<<endl;
}
return 0;
}