题解 | #平衡二叉树#

class Solution {
public:
    bool IsBalanced_Solution(TreeNode* pRoot) {
        int leftDeepth = 0;
        int rightDeepth = 0;
      	//空树直接返回true
        if(pRoot == nullptr) return true;
        //左子树不为空时，判断左子树是否为平衡树，若是平衡树求该子树深度，否则为空
        if(pRoot->left != nullptr){
            if( IsBalanced_Solution(pRoot->left) ) 
            {
                leftDeepth = treeDeepth(pRoot->left);
            }else return false;
        }
        //右子树不为空时，判断右子树是否为平衡树，若是平衡树求该子树深度，否则为空
        if(pRoot->right != nullptr){
            if(IsBalanced_Solution(pRoot->right))
            {
                rightDeepth = treeDeepth(pRoot->right);
            }else return false;
        }
        //判断左右子树高度差是否小于等于1
        if(abs(leftDeepth - rightDeepth)<=1) return true;
        else return false;
    }
    //树的深度
    int treeDeepth(TreeNode * pRoot)
    {
        if(pRoot == nullptr) return 0;
        return ( treeDeepth(pRoot->left) > treeDeepth(pRoot->right)? 
                 treeDeepth(pRoot->left) : treeDeepth(pRoot->right) ) + 1;
    }
};