LeetCode 101. Symmetric Tree

描述

解决

/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
bool isSymmetric(TreeNode* root) {
if (!root)
{
return true;
}
else
{
return judge(root -> left, root -> right);
}
}
bool judge(TreeNode* n1, TreeNode* n2)
{
if (!n1 && !n2)
{
return true;
}
else if ((!n1 && n2) || (n1 && !n2))
{
return false;
}
else
{
return n1 -> val == n2 -> val && judge(n1 -> left, n2 -> right) && judge(n1 -> right, n2 -> left);
}
}
};

/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
bool isSymmetric(TreeNode* root) {
queue<TreeNode*> que;
if (!root)
return true;
que.push(root);
que.push(root);
TreeNode* l = NULL, *r = NULL;
while (!que.empty())
{
l = que.front();
que.pop();
r = que.front();
que.pop();
if (!l && !r)
continue;
else if ((!l && r) || (!r && l))
return false;
else if (l -> val != r -> val)
return false;
que.push(l -> left);
que.push(r -> right);
que.push(l -> right);
que.push(r -> left);
}
return true;
}
};