Problem Statement
Pattern:
Solution
public int checkHeight (TreeNode root) {
if (root == null) return 0;
int lh = checkHeight(root.left);
int rh = checkHeight(root.right);
if(lh == -1 || rh == -1 || Math.abs(lh-rh) > 1) return -1;
// return height of current node
return Math.max(lh, rh) + 1;
}
public boolean isBalanced(TreeNode root) {
if(checkHeight(root) != -1) return true;
return false;
}Notes
- use int, to return the height difference at every step
- if height diff > 1 in current or left or right nodes, return -1
- if final value is not -1 return true, else return false