Balanced Binary Tree LeetCode solution in C++

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class Solution {
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 public:
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  bool isBalanced(TreeNode *root) {
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    // If the tree is empty, we can say it’s balanced...
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    if (root == NULL) return true;
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    // Height Function will return -1, when it’s an unbalanced tree...
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    if (Height(root) == -1) return false;
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    return true;
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  }
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  // Create a function to return the “height” of a current subtree using
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  // recursion...
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  int Height(TreeNode *root) {
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    // Base case...
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    if (root == NULL) return 0;
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    // Height of left subtree...
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    int leftHeight = Height(root->left);
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    // Height of height subtree...
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    int rightHight = Height(root->right);
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    // In case of left subtree or right subtree unbalanced or their heights
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    // differ by more than ‘1’, return -1...
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    if (leftHeight == -1 || rightHight == -1 || abs(leftHeight - rightHight) > 1) return -1;
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    // Otherwise, return the height of this subtree as max(leftHeight,
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    // rightHight) + 1...
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    return max(leftHeight, rightHight) + 1;
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  }
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};