完全二叉树求节点个数
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222. Count Complete Tree Nodes
Medium
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Given a complete binary tree, count the number of nodes.
Note:
Definition of a complete binary tree from Wikipedia:
In a complete binary tree every level, except possibly the last, is completely filled, and all nodes in the last level are as far left as possible. It can have between 1 and 2h nodes inclusive at the last level h.
Example:
Input:
1
/ \
2 3
/ \ /
4 5 6
Output: 6
class Solution {
public:
int countNodes(TreeNode* root) {
TreeNode* LeftNode = root;
TreeNode* RightNode = root;
int LeftNum = 0;
int RightNum = 0;
while(LeftNode){
LeftNum++;
LeftNode = LeftNode->left;
}
while(RightNode){
RightNum++;
RightNode = RightNode->right;
}
if(RightNum == LeftNum){
return pow(2,RightNum) - 1;
}
else{
return countNodes(root->left) + countNodes(root->right) + 1;
}
}
};