[Leetcode] Balanced Binary Tree

最新推荐文章于 2017-06-28 16:04:50 发布

原创最新推荐文章于 2017-06-28 16:04:50 发布 · 523 阅读

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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) {}
 * };
 */
class Solution {
public:
    bool isBalanced(TreeNode *n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (!n) return true;
        
        return isBalanced(n->left) && isBalanced(n->right) && abs(height(n->left) - height(n->right)) <= 1;
    }
    
    int height(TreeNode* n)
    {
        if (!n) return 0;
        
        return max(height(n->left), height(n->right)) + 1;
    }
};

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    bool isBalanced(TreeNode *root) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        
        int a = 0;
        return isBal(root, a);        
    }
    
    bool isBal(TreeNode* root, int& height)
    {
        if (!root) 
        {
            height = 0;
            return true;
        }
        
        int left = 0;
        int right = 0;
        if (!isBal(root->left, left)) return false;
        if (!isBal(root->right, right)) return false;
        
        height = max(left, right) + 1;
        return abs(left - right) <= 1;
    }
    
    
};