题目描述
请实现一个函数按照之字形打印二叉树，即第一行按照从左到右的顺序打印，第二层按照从右至左的顺序打印，第三行按照从左到右的顺序打印，其他行以此类推
思路：
用两个栈或队列去存储，用一个变量表示方向，根据不同方向存取顺序不同。
class Solution
{
public:
vector<vector<
int>> Print(TreeNode *
pRoot)
{
vector<vector<
int>>
res;
if (pRoot ==
NULL)
return res;
int direct =
1;
stack<TreeNode *>
staO;
stack<TreeNode *>
staE;
TreeNode *
cur;
staO.push(pRoot);
while (!staO.empty() || !
staE.empty())
{
vector<
int>
temp;
if (direct %
2 !=
0)
{
while (!
staO.empty())
{
cur =
staO.top();
staO.pop();
temp.push_back(cur->
val);
if (cur->left !=
NULL)
staE.push(cur->
left);
if (cur->right !=
NULL)
staE.push(cur->
right);
}
res.push_back(temp);
direct =
2;
}
else
{
while (!
staE.empty())
{
cur =
staE.top();
staE.pop();
temp.push_back(cur->
val);
if (cur->right !=
NULL)
staO.push(cur->
right);
if (cur->left !=
NULL)
staO.push(cur->
left);
}
res.push_back(temp);
direct =
1;
}
}
return res;
}
};
转载于:https://www.cnblogs.com/ruoh3kou/p/10244723.html
