[LeetCode] 110. Balanced Binary Tree (easy)

原题链接

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水题
深度搜索每一节点的左右深度，左右深度差大于1就返回false。

class Solution {
 public:
  bool isBalanced(TreeNode *root) {
    bool flag = true;
    if (!root) return true;
    dfs(root, flag);
    return flag;
  }

 private:
  int dfs(TreeNode *root, bool &flag) {
    if (!root) return 0;
    int leftH = dfs(root->left, flag) + 1;
    int rightH = dfs(root->right, flag) + 1;
    if (abs(leftH - rightH) > 1) flag = false;
    return max(leftH, rightH);
  }
};