[存档] 非递归后根遍历二叉树

 1 void NonRecursive_PostOrderTraversal(TreeNode *root){
 2     if(!root){
 3         cout<<"Empty tree"<<'\n';
 4         return;
 5     }
 6     stack<TreeNode *> s;
 7     TreeNode *cur = root;
 8     TreeNode *prev = root;
 9     s.push(root);
10     while(!s.empty()){
11         if(cur->Left && prev != cur->Left && prev != cur->Right){
12                 s.push(cur->Left); 
13                 prev = cur; 
14                 cur = cur->Left;
15                 continue; //如果有左子树且从未访问过，先访问左子树
16         }
17         if(cur->Right && prev !=cur->Right){
18             s.push(cur->Right); 
19             prev = cur; 
20             cur = cur->Right;
21         }else{
22             cout<<cur->Value<<", ";
23             prev = cur; 
24             s.pop(); 
25             if(!s.empty()){
26                 cur = s.top(); 
27             }
28         }
29     }
30     cout<<"end"<<'\n';
31 }