110.Balanced Binary Tree

Posted on | In

Solution 1: accepted

Use -1 as flag of inbalanced tree. Use another variable for better practice in production.

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class Solution {
    public boolean isBalanced(TreeNode root) {
        return maxDepth(root) != -1;
    }
    
    private int maxDepth(TreeNode root) {
        if (root == null) {
            return 0;
        }
        
        int left = maxDepth(root.left);
        int right = maxDepth(root.right);
        if (Math.abs(left - right) > 1 || left == -1 || right == -1) {
            return -1;
        }
        return Math.max(left, right) + 1;
    }
}