[leetcode] Balanced Binary Tree

要注意left-right 要用绝对值

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