一般来说，二叉树的遍历是C++程序员在面试中经常考察的，其实前中后三种顺序的遍历都大同小异，自己模拟两个栈用笔画画是不难写出代码的。现举一个非递归遍历的方法如下，供大家参考。
具体代码如下：
class Solution {
public:
vector<int> preorderTraversal(TreeNode *root) {
vector<int> out;
stack<TreeNode*> s;
s.push(root);
while(!s.empty() && root){
TreeNode *node = s.top();
out.push_back(node->val);
s.pop();
if(node->right) s.push(node->right);
if(node->left) s.push(node->left);
}
return out;
}
vector<int> inorderTraversal(TreeNode *root) {
stack<TreeNode *> s;
vector<int> out;
TreeNode *node = root;
bool done = false;
while(!done){
if(node){
s.push(node);
node = node->left;
}else {
if(s.empty()) done = true;
else{
node = s.top();
s.pop();
out.push_back(node->val);
node = node->right;
}
}
}
return out;
}
vector<int> postorderTraversal(TreeNode *root) {
vector<int> out;
stack<TreeNode*> s;
TreeNode* node = root;
s.push(node);
while(!s.empty()&&node){
node = s.top();
out.push_back(node->val);
s.pop();
if(node->left) s.push(node->left);
if(node->right)s.push(node->right);
}
reverse(out.begin(),out.end());
return out;
}
};
希望本文所述对大家的C++算法学习有所帮助。
