二分图判定 POJ-2492

这是由AC代码改的模板，不能直接交啊

#include<iostream>
#include<vector>
#include<cstring>
using namespace std;
int book[];
vector<int>v[];
bool dfs(int x,int c)
{
    book[x]=c;
    for(int i=;i<v[x].size();i++){
        if(book[v[x][i]]==c){return false;}
        if(book[v[x][i]]==&&!dfs(v[x][i],-c)){return false;}
    }
    return true;
}

int main()
{
    int T;
    cin>>T;
    int n,m,x,y;
    while(T--){
        memset(book,,sizeof(book));
        cin>>n>>m;
        for(int i=;i<m;i++){
            cin>>x>>y;
            v[x].push_back(y);
            v[y].push_back(x);
        }
        int flag=;
        for(int i=;i<=n;i++){
            if(!book[i]&&!dfs(i,)){flag=;break;}
        }
        if(flag){cout<<"非二分图"<<endl;}
        else cout<<"二分图"<<endl;
        for(int i=;i<=n;i++){
            v[i]=vector<int>();
        }
    }
}