水中的鱼

Give a string, which only contains a-z. List all the permutation of upcase and lowcase. For example, str = "ab",  the output shou...

Given a collection of intervals, merge all overlapping intervals. For example, Given  [1,3],[2,6],[8,10],[15,18] , return  [1,6],[8,10],...

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the ...

A very frequent interview question. Suppose you have a tree, how could you serialize it to file and revert it back? for example,       ...

Given a string containing just the characters  '('  and  ')' , find the length of the longest valid (well-formed) parenthe...

Given a string  s , partition  s  such that every substring of the partition is a palindrome. Return the minimum cuts needed for a palindr...

Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST. » Solve this problem [Tho...

Given a binary tree, return the  inorder  traversal of its nodes' values. For example: Given binary tree  {1,#,2,3} , 1 \ ...

Say you have an array for which the  i th  element is the price of a given stock on day  i . Design an algorithm to find the maximum pro...

Implement wildcard pattern matching with support for  '?'  and  '*' . '?' Matches any single character. '*...

Given a binary tree, determine if it is a valid binary search tree (BST). Assume a BST is defined as follows: The left subtree of a no...

Two elements of a binary search tree (BST) are swapped by mistake. Recover the tree without changing its structure. Note: A solution u...