68 - I. 二叉搜索树的最近公共祖先(lowestCommonAncestor)

68 - I. 二叉搜索树的最近公共祖先(lowestCommonAncestor)

1. python

class Solution:
    def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode':
        if not root or root ==p or root ==q:
            return root
        left = self.lowestCommonAncestor(root.left,p,q)
        right = self.lowestCommonAncestor(root.right,p,q)
        if left and right:
            return root
        else:
            return left if left else right

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2. Java

class Solution {
    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        if(root == null ||p==root ||q==root){
            return root;
        }
        TreeNode left = lowestCommonAncestor(root.left,p,q);
        TreeNode right =lowestCommonAncestor(root.right,p,q);
        if(left!=null &&right!=null){
            return root;
        }else{
            return left==null?right:left;
        }
        
    }
}

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