java 二叉树的最低共同祖先

Posted 2021-05-08

// This code assumes both nodes exist

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