一棵树是完全二叉树当且仅当每一个节点的左子树和右子树的深度之差都不大于1。
C++ 代码
/**
* 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 ans = true;
int dfs(TreeNode* root){
if (root == NULL){
return 0;
}
int left = dfs(root->left),right = dfs(root->right);
if (abs(left-right) > 1) ans = false;
return max(left,right) + 1;
}
bool isBalanced(TreeNode* root) {
dfs(root);
return ans;
}
};