题解 | #判断是不是平衡二叉树#

递归一直是弱项

class Solution {
  public:
    bool IsBalanced_Solution(TreeNode* pRoot) {
      return deepth(pRoot) != -1;
    }
  private:
    int deepth(TreeNode *root) {
      if (root == nullptr) {
        return 0;
      }
      
      int ldep = deepth(root->left);
      if (ldep == -1) {
        return -1;
      }
      
      int rdep = deepth(root->right);
      if (rdep == -1) {
        return -1;
      }
      
      int sub = std::abs(ldep - rdep);
      
      //  -1会一直向上传递
      if (sub > 1) {
        return -1;
      }
      
      return std::max(ldep, rdep) + 1;
    }
};