题解 | #判断是不是平衡二叉树#

/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 *	TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 * };
 */
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param pRoot TreeNode类 
     * @return bool布尔型
     */
    bool IsBalanced_Solution(TreeNode* pRoot) {
        auto hei = [](auto&& hei, TreeNode* n, size_t h) -> size_t {
            if (not n) return h;
            else return std::max(hei(hei, n->left, h), hei(hei, n->right, h)) + 1;
        };
        auto IsBal = [&hei](auto&& IsBal, TreeNode* node) -> bool {
            if(not node) return true;
            return std::abs<int>(hei(hei, node->left, 0) - hei(hei, node->right, 0)) <= 1 and IsBal(IsBal, node->left) and IsBal(IsBal, node->right);
        };
        return IsBal(IsBal, pRoot);
    }
};