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balancedtree.cpp
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balancedtree.cpp
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/**
* Definition for binary tree
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
Given a binary tree, determine if it is height-balanced.
For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.
*/
class Solution {
public:
bool isBalanced(TreeNode *root) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
if (root == NULL) return true;
// determine the left & right tree are ballanced
//
bool result = isBalanced( root-> left) && isBalanced(root->right);
int left_depth, right_depth;
// get the depth of left and right sub-tree
if (root->left != NULL)
left_depth = root -> left -> val;
else
left_depth = 0;
if (root -> right != NULL )
right_depth = root -> right -> val;
else
right_depth = 0;
// determine the depth of root
root -> val = right_depth + 1;
if (left_depth > right_depth)
root -> val = left_depth + 1;
result = ( result && (right_depth - left_depth > -2) && (right_depth - left_depth < 2 ));
return result;
}
};