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countCBTnodes.cpp
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countCBTnodes.cpp
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/**
* 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:
vector<int> helper(TreeNode* t) {
vector<int> level(2, 0);
if(t) {
for(TreeNode* p = t; p ; p = p->left, level[0]++) {}
for(TreeNode* p = t; p ; p = p->right, level[1]++) {}
}
return level;
}
int countNodes(TreeNode* root) {
if(!root)
return 0;
vector<int> level = helper(root->left);
if(level[0] == level[1])
return pow(2, level[0]) + countNodes(root->right);
else
return pow(2, level[1]) + countNodes(root->left);
}
};
class Solution {
public:
int countNodes(TreeNode* root) {
if(!root) return 0;
int hl=0, hr=0;
TreeNode *l=root, *r=root;
while(l) {hl++;l=l->left;}
while(r) {hr++;r=r->right;}
if(hl==hr) return pow(2,hl)-1;
return 1+countNodes(root->left)+countNodes(root->right);
}
};