g0101_0200.s0110_balanced_binary_tree.Solution Maven / Gradle / Ivy

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package g0101_0200.s0110_balanced_binary_tree;

import com_github_leetcode.TreeNode;

public class Solution {
    public boolean isBalanced(TreeNode root) {

        // Empty Tree is balanced
        if (root == null) {
            return true;
        }

        // Get max height of subtree child
        // Get max height of subtree child
        // compare height difference (cannot be more than 1)
        int leftHeight = 0;
        int rightHeight = 0;

        if (root.left != null) {
            leftHeight = getMaxHeight(root.left);
        }

        if (root.right != null) {
            rightHeight = getMaxHeight(root.right);
        }

        int heightDiff = Math.abs(leftHeight - rightHeight);

        // if passes height check
        //  - Check if left subtree is balanced and if the right subtree is balanced
        //  - If one of both are imbalanced, then the tree is imbalanced
        boolean isBalanced = false;
        if (heightDiff <= 1 && isBalanced(root.left) && isBalanced(root.right)) {

            isBalanced = true;
        }
        return isBalanced;
    }

    public int getMaxHeight(TreeNode root) {

        if (root == null) {
            return 0;
        }

        int leftHeight = 0;
        int rightHeight = 0;

        // Left
        if (root.left != null) {
            leftHeight = getMaxHeight(root.left);
        }

        // Right
        if (root.right != null) {
            rightHeight = getMaxHeight(root.right);
        }

        if (leftHeight > rightHeight) {
            return 1 + leftHeight;
        } else {
            return 1 + rightHeight;
        }
    }
}