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Balanced_Binary_Tree.cpp
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46 lines (40 loc) · 1.19 KB
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/*
Author: Timon Cui, [email protected]
Title: Balanced Binary Tree
Description:
Given a binary tree, determine if it is height-balanced.
For this problem, a height-balanced binary tree is defined as a binary tree
in which the depth of the two subtrees of every node never differ by more than 1.
Difficulty rating: Medium
Notes: The trick is to orchestrate the order of traversal properly so that
no node is visited more than once, maintaining O(n) complexity.
*/
/**
* Definition for binary tree
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
bool isBalanced(TreeNode *root) {
int depth;
return isBalancedWithDepth(root, depth);
}
private:
bool isBalancedWithDepth(TreeNode *root, int& depth) {
if (!root) {
depth = 0;
return true;
}
int depth_l, depth_r;
bool res = isBalancedWithDepth(root->left, depth_l);
if (!res) return false;
res &= isBalancedWithDepth(root->right, depth_r);
depth = max(depth_l, depth_r) + 1;
return res && (abs(depth_l - depth_r) <= 1);
}
};