面试题60 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>> v;
vector<int> vc;
stack<TreeNode*> s1;
stack<TreeNode*> s2;
queue<TreeNode*> q;

vector<vector<int>> Print(TreeNode* pRoot) {
if (!pRoot)
return v;
q.push(pRoot);
while (!s1.empty() || !q.empty()){
while (!q.empty()){
vc.push_back(q.front()->val);
if (q.front()->left != NULL)
s1.push(q.front()->left);
if (q.front()->right != NULL)
s1.push(q.front()->right);
q.pop();
}
if (!vc.empty()){
v.push_back(vc);
vc.clear();
}

while (!s1.empty()){
vc.push_back(s1.top()->val);
s2.push(s1.top());
s1.pop();
}
while (!s2.empty()){
if (s2.top()->left != NULL)
q.push(s2.top()->left);
if (s2.top()->right != NULL)
q.push(s2.top()->right);
s2.pop();
}
if (!vc.empty()){
v.push_back(vc);
vc.clear();
}
}
return v;
}

};