Lowest Common Ancestor of a Binary Search Tree

see lca of binary tree.

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5. Longest Palindromic Substring

Problem: Given a string  s , find the longest palindromic substring in  s . You may assume that the maximum length of  s  is 1000. Example: Input: "babad" Output: "bab" Note: "aba" is also a valid answer. Example: Input: "cbbd" Output: "bb" 5/22/2018 update: No need to think about after while loop, whether start and end are valid or not. Just update palindrome length within the loop. class Solution { int max = 1 ; int start = 0 ; public String longestPalindrome ( String s) { if (s == null || s . length() == 0 ) return "" ; for ( int i = 0 ; i < s . length() - 1 ; i ++ ) { computePalindrome(s, i, i); computePalindrome(s, i, i + 1 ); } return s . substring(start, start + max); } private void computePalindrome ( String s, int l, int r) { int temp = 0 , len = 0 ; while (l ...
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776. Split BST

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Problem: Given a Binary Search Tree (BST) with root node  root , and a target value  V , split the tree into two subtrees where one subtree has nodes that are all smaller or equal to the target value, while the other subtree has all nodes that are greater than the target value.  It's not necessarily the case that the tree contains a node with value  V . Additionally, most of the structure of the original tree should remain.  Formally, for any child C with parent P in the original tree, if they are both in the same subtree after the split, then node C should still have the parent P. You should output the root TreeNode of both subtrees after splitting, in any order. Example 1: Input: root = [4,2,6,1,3,5,7], V = 2 Output: [[2,1],[4,3,6,null,null,5,7]] Explanation: Note that root, output[0], and output[1] are TreeNode objects, not arrays. The given tree [4,2,6,1,3,5,7] is represented by the following diagram: 4 / \ ...
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