PTA 03-树2 List Leaves（25 分）

先是找到根节点在哪，然后层序遍历；

#include<iostream>#define MaxTree 10#define Tree char #include<vector>#include<queue>using namespace std;struct TreeNode{int index;Tree Left;Tree Right;int leftnumber;int rightnumber;}T1[MaxTree];queue<TreeNode>q;int main(){int n;cin>>n;int check[10]; for(int i=0;i<n;i++)  check[i]=0;for(int i=0;i<n;i++){T1[i].index=i; cin>>T1[i].Left>>T1[i].Right;if(T1[i].Left!='-'){T1[i].leftnumber=T1[i].Left-'0';check[T1[i].leftnumber]=1; }else  T1[i].leftnumber=-1;  if(T1[i].Right!='-'){T1[i].rightnumber=T1[i].Right-'0';check[T1[i].rightnumber]=1;}else  T1[i].rightnumber=-1;  }int Root;for(int i=0;i<n;i++)//找根结点   if(!check[i])   {     Root=i;     break;   }//cout<<Root<<endl;       q.push(T1[Root]);    int count = 0;    //cout<<"hello world"<<endl;    while(!q.empty())//层序遍历    {    TreeNode heel =q.front();    q.pop();    if(heel.leftnumber!=-1)    {    q.push(T1[heel.leftnumber]); }if(heel.rightnumber!=-1){q.push(T1[heel.rightnumber]);}if(heel.leftnumber==-1&&heel.rightnumber==-1){if(count == 0){cout<<heel.index;count=1;}else  cout<<" "<<heel.index;}}return 0;}