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.
Example
No.1
Given the following tree [3,9,20,null,null,15,7]:
Return true.
No.2
Given the following tree [1,2,2,3,3,null,null,4,4]:
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1
/
2 2
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3 3
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4 4
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Return false.
Code
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public class {
int val;
TreeNode left;
TreeNode right;
TreeNode(int x) { val = x; }
}
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public boolean isBalanced(TreeNode root) {
return maxDepth(root) == -1 ? false : true;
}
private int maxDepth(TreeNode root) {
if (root == null)
return 0;
int leftDepth = maxDepth(root.left);
if (leftDepth == -1)
return -1;
int rightDepth = maxDepth(root.right);
if (rightDepth == -1)
return -1;
return (Math.abs(leftDepth - rightDepth) > 1) ? -1 : Math.max(leftDepth, rightDepth) + 1;
}
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