【二叉树】平衡二叉树

解题思路：递归解决

递归结束条件：传入结点为NULL

1.求出左右子树最大深度，进行比较：

若差值大于1，则为false

2.递归左右子树，再进行比较

int getDepth(struct TreeNode* node) {
    if(!node)
        return 0;
    int left = getDepth(node->left);
    int right = getDepth(node->right);
    return (left < right ? right : left)+1;
}

bool isBalanced(struct TreeNode* root){
    if(!root)
        return 1;
    int lDepth = getDepth(root->left);
    printf("%d\\n",lDepth);
    int rDepth = getDepth(root->right);
    printf("%d",rDepth);
    return ((lDepth - rDepth) <= 1 && (lDepth - rDepth) >= -1)&& isBalanced(root->left) && isBalanced(root->right);
}