【LeetCode】Balanced Binary Tree

递归检查每个节点其左右子树最大深度差不超过1即可。

/**
 * Definition for binary tree
 * struct TreeNode {
 * int val;
 * TreeNode *left;
 * TreeNode *right;
 * TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    void depth(TreeNode *node, int dep, int *maxdep)
    {
        if(NULL==node) {if(*maxdep<dep) *maxdep=dep; return;}
        dep++;
        depth(node->left, dep, maxdep);
        depth(node->right, dep, maxdep);
    }
    bool isBalanced(TreeNode *root) {
        if(NULL==root) return true;
        int leftdep=0;
        int rightdep=0;
        depth(root->left,0,&leftdep);
        depth(root->right,0,&rightdep);
        if(abs(leftdep-rightdep)>1) return false;
        return isBalanced(root->left)&&isBalanced(root->right);
    }
};