PAT A 1094. The Largest Generation (25)

就是很简单的树的层次遍历。

#include <cstdio>#include <vector>#include <queue>using namespace std;vector<int> child[100];queue<int> q;void BFS(int &max,int &maxlevel){int p=1,level=1,end=1;max=1,maxlevel=1;while(!q.empty())q.pop();q.push(p);while(!q.empty()){p=q.front();q.pop();if(!child[p].empty()){//将p的所有孩子压入队列for(int c:child[p])q.push(c);}if(end==p){++level;if(max<q.size()){maxlevel=level;max=q.size();}if(!q.empty())end=q.back();}}}int main(void){//freopen("in.log","r",stdin);int m,n,max,maxlevel;scanf("%d%d",&n,&m);while(m--){int id,tmpn;scanf("%d%d",&id,&tmpn);while(tmpn--){int tmpid;scanf("%d",&tmpid);child[id].push_back(tmpid);}}BFS(max,maxlevel);printf("%d %d",max,maxlevel);return 0;}