hdu 1689 Alien’s Necklace

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输出节点数为奇数且最小环的节点数

开始开2维数组果断超内存，看了别人的代码才知道用奇偶性来标记

#include<iostream>#include<vector>#include<queue>#include<cstring>#define maxn 10000+1using namespace std;vector<int>mapp[maxn];int n,m;int visit[maxn][2];struct stu{int pre;int now;int deep;};int bfs(int p){queue<stu>root;stu x,y;x.pre=-1;x.now=p;x.deep=0;root.push(x);while(root.size()){x=root.front();root.pop();if(x.now==p&&x.deep>=3&&x.deep%2) return x.deep;else if(x.now==p&&x.deep!=0) continue; for(int i=0;i<mapp[x.now].size();i++){if(mapp[x.now][i]!=x.pre&&!visit[mapp[x.now][i]][(x.deep+1)%2]){y.pre=x.now;y.now=mapp[x.now][i];y.deep=x.deep+1;visit[y.now][y.deep%2]=1;root.push(y);}  }}return 1<<30;}int main(){cin.sync_with_stdio(false);int t;cin>>t;int casee=1;while(t--){cin>>n>>m;for(int i=1;i<=n;i++)  mapp[i].clear();for(int i=0;i<m;i++){int x,y;cin>>x>>y;mapp[x].push_back(y);mapp[y].push_back(x);}int ans=1<<30;for(int i=1;i<=n;i++){memset(visit,0,sizeof(visit));ans=min(ans,bfs(i));}cout<<"Case "<<casee++<<": ";if(ans!=1<<30) cout<<"JYY has to use "<<ans<<" balls."<<endl;else cout<<"Poor JYY."<<endl;}return 0;}

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