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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.
源码：
Java版本
算法分析：使用栈。时间复杂度O(n)，空间复杂度O(logn)
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/**
* Definition for binary tree
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public boolean isBalanced(TreeNode root) {
return balancedHeight(root)>=0?true:false;
}
private int balancedHeight(TreeNode root) {
if(root==null) {
return 0;
}
int left=balancedHeight(root.left);
int right=balancedHeight(root.right);
if(left<0 || right <0 || Math.abs(left-right)>1) {
return -1;
}
return Math.max(left,right)+1;
}
}
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