按之字形顺序打印二叉树

题目描述

/*
struct TreeNode {
int val;
struct TreeNode *left;
struct TreeNode *right;
TreeNode(int x) :
val(x), left(NULL), right(NULL) {
}
};
*/
class Solution {
public:
vector<vector<int> > Print(TreeNode* pRoot) {
vector<vector<int> > result;

if(pRoot == NULL)
return result;

stack<TreeNode*> stk1;
stack<TreeNode*> stk2;
stk1.push(pRoot);
TreeNode* tmp;
vector<int> tLevel;

while(!stk1.empty() || !stk2.empty())
{
if(!stk1.empty())
{
while(!stk1.empty())
{
tmp=stk1.top();
tLevel.push_back(tmp->val);
if(tmp->left)
stk2.push(tmp->left);
if(tmp->right)
stk2.push(tmp->right);
stk1.pop();
}
result.push_back(tLevel);
tLevel.clear();
}
else
{
while(!stk2.empty())
{
tmp=stk2.top();
tLevel.push_back(tmp->val);
if(tmp->right)
stk1.push(tmp->right);
if(tmp->left)
stk1.push(tmp->left);
stk2.pop();
}
result.push_back(tLevel);
tLevel.clear();
}
}
return result;
}

};